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data-event-name="pinnable-header.vector-toc.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-toc.unpin">hide</button> </div> <ul class="vector-toc-contents" id="mw-panel-toc-list"> <li id="toc-mw-content-text" class="vector-toc-list-item vector-toc-level-1"> <a href="#" class="vector-toc-link"> <div class="vector-toc-text">(Top)</div> </a> </li> <li id="toc-Function" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Function"> <div class="vector-toc-text"> <span class="vector-toc-numb">1</span> <span>Function</span> </div> </a> <ul id="toc-Function-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Reactions" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Reactions"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Reactions</span> </div> </a> <button aria-controls="toc-Reactions-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Reactions subsection</span> </button> <ul id="toc-Reactions-sublist" class="vector-toc-list"> <li id="toc-First_reaction:_entering_the_urea_cycle" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#First_reaction:_entering_the_urea_cycle"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.1</span> <span>First reaction: entering the urea cycle</span> </div> </a> <ul id="toc-First_reaction:_entering_the_urea_cycle-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Steps_of_the_urea_cycle" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Steps_of_the_urea_cycle"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.2</span> <span>Steps of the urea cycle</span> </div> </a> <ul id="toc-Steps_of_the_urea_cycle-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Overall_reaction_equation" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Overall_reaction_equation"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.3</span> <span>Overall reaction equation</span> </div> </a> <ul id="toc-Overall_reaction_equation-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Products_of_the_urea_cycle" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Products_of_the_urea_cycle"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Products of the urea cycle</span> </div> </a> <ul id="toc-Products_of_the_urea_cycle-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Regulation" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Regulation"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Regulation</span> </div> </a> <button aria-controls="toc-Regulation-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Regulation subsection</span> </button> <ul id="toc-Regulation-sublist" class="vector-toc-list"> <li id="toc-N-Acetylglutamic_acid" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#N-Acetylglutamic_acid"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1</span> <span><i>N</i>-Acetylglutamic acid</span> </div> </a> <ul id="toc-N-Acetylglutamic_acid-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Substrate_concentrations" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Substrate_concentrations"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2</span> <span>Substrate concentrations</span> </div> </a> <ul id="toc-Substrate_concentrations-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Link_with_the_citric_acid_cycle" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Link_with_the_citric_acid_cycle"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Link with the citric acid cycle</span> </div> </a> <ul id="toc-Link_with_the_citric_acid_cycle-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Urea_cycle_disorders" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Urea_cycle_disorders"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Urea cycle disorders</span> </div> </a> <button aria-controls="toc-Urea_cycle_disorders-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Urea cycle disorders subsection</span> </button> <ul id="toc-Urea_cycle_disorders-sublist" class="vector-toc-list"> <li id="toc-Individual_disorders" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Individual_disorders"> <div class="vector-toc-text"> <span class="vector-toc-numb">6.1</span> <span>Individual disorders</span> </div> </a> <ul id="toc-Individual_disorders-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Additional_images" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Additional_images"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>Additional images</span> </div> </a> <ul id="toc-Additional_images-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">9</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Urea cycle</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" 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Available in 40 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-40" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">40 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%AF%D9%88%D8%B1%D8%A9_%D8%A7%D9%84%D9%8A%D9%88%D8%B1%D9%8A%D8%A7" title="دورة اليوريا – Arabic" lang="ar" hreflang="ar" data-title="دورة اليوريا" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%9E%D1%80%D0%BD%D0%B8%D1%82%D0%B8%D0%BD%D0%BE%D0%B2_%D1%86%D0%B8%D0%BA%D1%8A%D0%BB" title="Орнитинов цикъл – Bulgarian" lang="bg" hreflang="bg" data-title="Орнитинов цикъл" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-bs mw-list-item"><a href="https://bs.wikipedia.org/wiki/Ciklus_ureje" title="Ciklus ureje – Bosnian" lang="bs" hreflang="bs" data-title="Ciklus ureje" data-language-autonym="Bosanski" data-language-local-name="Bosnian" class="interlanguage-link-target"><span>Bosanski</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Cicle_de_la_urea" title="Cicle de la urea – Catalan" lang="ca" hreflang="ca" data-title="Cicle de la urea" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Mo%C4%8Dovinov%C3%BD_cyklus" title="Močovinový cyklus – Czech" lang="cs" hreflang="cs" data-title="Močovinový cyklus" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Harnstoffzyklus" title="Harnstoffzyklus – German" lang="de" hreflang="de" data-title="Harnstoffzyklus" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/%CE%9A%CF%8D%CE%BA%CE%BB%CE%BF%CF%82_%CF%84%CE%B7%CF%82_%CE%BF%CF%85%CF%81%CE%AF%CE%B1%CF%82" title="Κύκλος της ουρίας – Greek" lang="el" hreflang="el" data-title="Κύκλος της ουρίας" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Ciclo_de_la_urea" title="Ciclo de la urea – Spanish" lang="es" hreflang="es" data-title="Ciclo de la urea" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Urea_ciklo" title="Urea ciklo – Esperanto" lang="eo" hreflang="eo" data-title="Urea ciklo" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%DA%86%D8%B1%D8%AE%D9%87_%D8%A7%D9%88%D8%B1%D9%87" title="چرخه اوره – Persian" lang="fa" hreflang="fa" data-title="چرخه اوره" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Cycle_de_l%27ur%C3%A9e" title="Cycle de l'urée – French" lang="fr" hreflang="fr" data-title="Cycle de l'urée" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Ciclo_da_urea" title="Ciclo da urea – Galician" lang="gl" hreflang="gl" data-title="Ciclo da urea" data-language-autonym="Galego" data-language-local-name="Galician" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EC%9A%94%EC%86%8C_%ED%9A%8C%EB%A1%9C" title="요소 회로 – Korean" lang="ko" hreflang="ko" data-title="요소 회로" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/Ciklus_ureje" title="Ciklus ureje – Croatian" lang="hr" hreflang="hr" data-title="Ciklus ureje" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Ciclo_dell%27urea" title="Ciclo dell'urea – Italian" lang="it" hreflang="it" data-title="Ciclo dell'urea" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%9E%D7%A2%D7%92%D7%9C_%D7%94%D7%90%D7%95%D7%A8%D7%99%D7%90%D7%94" title="מעגל האוריאה – Hebrew" lang="he" hreflang="he" data-title="מעגל האוריאה" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-la mw-list-item"><a href="https://la.wikipedia.org/wiki/Cyclus_ureae" title="Cyclus ureae – Latin" lang="la" hreflang="la" data-title="Cyclus ureae" data-language-autonym="Latina" data-language-local-name="Latin" class="interlanguage-link-target"><span>Latina</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/Karbamidciklus" title="Karbamidciklus – Hungarian" lang="hu" hreflang="hu" data-title="Karbamidciklus" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%A6%D0%B8%D0%BA%D0%BB%D1%83%D1%81_%D0%BD%D0%B0_%D1%83%D1%80%D0%B5%D0%B0" title="Циклус на уреа – Macedonian" lang="mk" hreflang="mk" data-title="Циклус на уреа" data-language-autonym="Македонски" data-language-local-name="Macedonian" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Kitaran_urea" title="Kitaran urea – Malay" lang="ms" hreflang="ms" data-title="Kitaran urea" data-language-autonym="Bahasa Melayu" data-language-local-name="Malay" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Ureumcyclus" title="Ureumcyclus – Dutch" lang="nl" hreflang="nl" data-title="Ureumcyclus" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E5%B0%BF%E7%B4%A0%E5%9B%9E%E8%B7%AF" title="尿素回路 – Japanese" lang="ja" hreflang="ja" data-title="尿素回路" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/Ureasyklus" title="Ureasyklus – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="Ureasyklus" data-language-autonym="Norsk nynorsk" data-language-local-name="Norwegian Nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Cykl_ornitynowy" title="Cykl ornitynowy – Polish" lang="pl" hreflang="pl" data-title="Cykl ornitynowy" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Ciclo_da_ureia" title="Ciclo da ureia – Portuguese" lang="pt" hreflang="pt" data-title="Ciclo da ureia" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/Ciclul_ureei" title="Ciclul ureei – Romanian" lang="ro" hreflang="ro" data-title="Ciclul ureei" data-language-autonym="Română" data-language-local-name="Romanian" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%A6%D0%B8%D0%BA%D0%BB_%D0%BC%D0%BE%D1%87%D0%B5%D0%B2%D0%B8%D0%BD%D1%8B" title="Цикл мочевины – Russian" lang="ru" hreflang="ru" data-title="Цикл мочевины" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Mo%C4%8Dovinov%C3%BD_cyklus" title="Močovinový cyklus – Slovak" lang="sk" hreflang="sk" data-title="Močovinový cyklus" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/Ciklus_se%C4%8Dnine" title="Ciklus sečnine – Slovenian" lang="sl" hreflang="sl" data-title="Ciklus sečnine" data-language-autonym="Slovenščina" data-language-local-name="Slovenian" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/%D0%A6%D0%B8%D0%BA%D0%BB%D1%83%D1%81_%D1%83%D1%80%D0%B5%D1%98%D0%B5" title="Циклус уреје – Serbian" lang="sr" hreflang="sr" data-title="Циклус уреје" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/Ciklus_ureje" title="Ciklus ureje – Serbo-Croatian" lang="sh" hreflang="sh" data-title="Ciklus ureje" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="Serbo-Croatian" class="interlanguage-link-target"><span>Srpskohrvatski / српскохрватски</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Ureakierto" title="Ureakierto – Finnish" lang="fi" hreflang="fi" data-title="Ureakierto" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Ureacykeln" title="Ureacykeln – Swedish" lang="sv" hreflang="sv" data-title="Ureacykeln" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%AF%E0%AF%82%E0%AE%B0%E0%AE%BF%E0%AE%AF%E0%AE%BE_%E0%AE%9A%E0%AF%81%E0%AE%B4%E0%AE%B1%E0%AF%8D%E0%AE%9A%E0%AE%BF" title="யூரியா சுழற்சி – Tamil" lang="ta" hreflang="ta" data-title="யூரியா சுழற்சி" data-language-autonym="தமிழ்" data-language-local-name="Tamil" class="interlanguage-link-target"><span>தமிழ்</span></a></li><li class="interlanguage-link interwiki-th mw-list-item"><a href="https://th.wikipedia.org/wiki/%E0%B8%A7%E0%B8%B1%E0%B8%8F%E0%B8%88%E0%B8%B1%E0%B8%81%E0%B8%A3%E0%B8%A2%E0%B8%B9%E0%B9%80%E0%B8%A3%E0%B8%B5%E0%B8%A2" title="วัฏจักรยูเรีย – Thai" lang="th" hreflang="th" data-title="วัฏจักรยูเรีย" data-language-autonym="ไทย" data-language-local-name="Thai" class="interlanguage-link-target"><span>ไทย</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/%C3%9Cre_d%C3%B6ng%C3%BCs%C3%BC" title="Üre döngüsü – Turkish" lang="tr" hreflang="tr" data-title="Üre döngüsü" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%A6%D0%B8%D0%BA%D0%BB_%D1%81%D0%B5%D1%87%D0%BE%D0%B2%D0%B8%D0%BD%D0%B8" title="Цикл сечовини – Ukrainian" lang="uk" hreflang="uk" data-title="Цикл сечовини" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/Chu_tr%C3%ACnh_ure" title="Chu trình ure – Vietnamese" lang="vi" hreflang="vi" data-title="Chu trình ure" data-language-autonym="Tiếng Việt" data-language-local-name="Vietnamese" class="interlanguage-link-target"><span>Tiếng Việt</span></a></li><li class="interlanguage-link interwiki-yo mw-list-item"><a href="https://yo.wikipedia.org/wiki/Urea_cycle" title="Urea cycle – Yoruba" lang="yo" hreflang="yo" data-title="Urea cycle" data-language-autonym="Yorùbá" data-language-local-name="Yoruba" class="interlanguage-link-target"><span>Yorùbá</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E5%B0%BF%E7%B4%A0%E5%BE%AA%E7%8E%AF" title="尿素循环 – Chinese" lang="zh" hreflang="zh" data-title="尿素循环" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q595994#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></span></div> </div> </div> </div> </header> 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cycle of <a href="/wiki/Biochemistry" title="Biochemistry">biochemical</a> reactions that produces <a href="/wiki/Urea" title="Urea">urea</a> (NH<sub>2</sub>)<sub>2</sub>CO from <a href="/wiki/Ammonia" title="Ammonia">ammonia</a> (NH<sub>3</sub>). Animals that use this cycle, mainly amphibians and mammals, are called <a href="/wiki/Ureotelic" class="mw-redirect" title="Ureotelic">ureotelic</a>. </p><p>The urea cycle converts highly toxic ammonia to urea for excretion.<sup id="cite_ref-:0_1-0" class="reference"><a href="#cite_note-:0-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> This cycle was the first metabolic cycle to be discovered by <a href="/wiki/Hans_Adolf_Krebs" class="mw-redirect" title="Hans Adolf Krebs">Hans Krebs</a> and <a href="/wiki/Kurt_Henseleit" title="Kurt Henseleit">Kurt Henseleit</a> in 1932,<sup id="cite_ref-Krebs1932a_2-0" class="reference"><a href="#cite_note-Krebs1932a-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Krebs1932b_3-0" class="reference"><a href="#cite_note-Krebs1932b-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Krebs1932c_4-0" class="reference"><a href="#cite_note-Krebs1932c-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> five years before the discovery of the <a href="/wiki/TCA_cycle" class="mw-redirect" title="TCA cycle">TCA cycle</a>. The urea cycle was described in more detail later on by Ratner and Cohen. The urea cycle takes place primarily in the <a href="/wiki/Liver" title="Liver">liver</a> and, to a lesser extent, in the <a href="/wiki/Kidney" title="Kidney">kidneys</a>. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Function">Function</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Urea_cycle&action=edit&section=1" title="Edit section: Function"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Amino_acid_catabolism" class="mw-redirect" title="Amino acid catabolism">Amino acid catabolism</a> results in waste ammonia. All animals need a way to excrete this product. Most <a href="/wiki/Aquatic_animal" title="Aquatic animal">aquatic organisms</a>, or <a href="/wiki/Metabolic_waste" title="Metabolic waste">ammonotelic</a> organisms, excrete ammonia without converting it.<sup id="cite_ref-:0_1-1" class="reference"><a href="#cite_note-:0-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> Organisms that cannot easily and safely remove nitrogen as ammonia convert it to a less toxic substance, such as <a href="/wiki/Urea" title="Urea">urea</a>, via the urea cycle, which occurs mainly in the liver. Urea produced by the liver is then released into the <a href="/wiki/Circulatory_system" title="Circulatory system">bloodstream</a>, where it travels to the <a href="/wiki/Kidney" title="Kidney">kidneys</a> and is ultimately excreted in <a href="/wiki/Urine" title="Urine">urine</a>. The urea cycle is essential to these organisms, because if the nitrogen or ammonia is not eliminated from the organism it can be very detrimental.<sup id="cite_ref-:122_5-0" class="reference"><a href="#cite_note-:122-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> In species including <a href="/wiki/Bird" title="Bird">birds</a> and most <a href="/wiki/Insect" title="Insect">insects</a>, the ammonia is converted into <a href="/wiki/Uric_acid" title="Uric acid">uric acid</a> or its <a href="/wiki/Uric_acid" title="Uric acid">urate</a> salt, which is excreted in <a href="/wiki/Salt" title="Salt">solid form</a>. Further, the urea cycle consumes acidic waste carbon dioxide by combining it with the basic ammonia, helping to maintain a neutral pH. </p> <div class="mw-heading mw-heading2"><h2 id="Reactions">Reactions</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Urea_cycle&action=edit&section=2" title="Edit section: Reactions"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The entire process converts two amino groups, one from <span class="chemf nowrap">NH<span class="nowrap"><span style="display:inline-block;margin-bottom:-0.3em;vertical-align:-0.4em;line-height:1em;font-size:80%;text-align:left"><sup style="font-size:inherit;line-height:inherit;vertical-align:baseline">+</sup><br /><sub style="font-size:inherit;line-height:inherit;vertical-align:baseline">4</sub></span></span></span> and one from <a href="/wiki/Aspartic_acid" title="Aspartic acid">aspartate</a>, and a carbon atom from <span class="chemf nowrap">HCO<span class="nowrap"><span style="display:inline-block;margin-bottom:-0.3em;vertical-align:-0.4em;line-height:1em;font-size:80%;text-align:left"><sup style="font-size:inherit;line-height:inherit;vertical-align:baseline">−</sup><br /><sub style="font-size:inherit;line-height:inherit;vertical-align:baseline">3</sub></span></span></span>, to the relatively nontoxic excretion product <a href="/wiki/Urea" title="Urea">urea</a>.<sup id="cite_ref-:2_6-0" class="reference"><a href="#cite_note-:2-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> This occurs at the cost of four "high-energy" <a href="/wiki/Phosphate" title="Phosphate">phosphate</a> bonds (3 ATP hydrolyzed to 2 <a href="/wiki/Adenosine_diphosphate" title="Adenosine diphosphate">ADP</a> and one <a href="/wiki/Adenosine_monophosphate" title="Adenosine monophosphate">AMP</a>). The conversion from ammonia to urea happens in five main steps. The first is needed for ammonia to enter the cycle and the following four are all a part of the cycle itself. To enter the cycle, ammonia is converted to <a href="/wiki/Carbamoyl_phosphate" title="Carbamoyl phosphate">carbamoyl phosphate</a>. The urea cycle consists of four enzymatic reactions: one <a href="/wiki/Mitochondria" class="mw-redirect" title="Mitochondria">mitochondrial</a> and three <a href="/wiki/Cytosol" title="Cytosol">cytosolic</a>.<sup id="cite_ref-:0_1-2" class="reference"><a href="#cite_note-:0-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-:3_7-0" class="reference"><a href="#cite_note-:3-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> This uses 6 enzymes.<sup id="cite_ref-:2_6-1" class="reference"><a href="#cite_note-:2-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-:3_7-1" class="reference"><a href="#cite_note-:3-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-:4_8-0" class="reference"><a href="#cite_note-:4-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p> <table class="wikitable"> <caption>Reactions of the urea cycle </caption> <tbody><tr> <th>Step</th> <th>Reactants</th> <th>Products</th> <th>Catalyzed by</th> <th>Location </th></tr> <tr> <th>1 </th> <td>NH<sub>3</sub> + <span class="chemf nowrap">HCO<span class="nowrap"><span style="display:inline-block;margin-bottom:-0.3em;vertical-align:-0.4em;line-height:1em;font-size:80%;text-align:left"><sup style="font-size:inherit;line-height:inherit;vertical-align:baseline">−</sup><br /><sub style="font-size:inherit;line-height:inherit;vertical-align:baseline">3</sub></span></span></span> + 2<a href="/wiki/Adenosine_triphosphate" title="Adenosine triphosphate">ATP</a></td> <td><a href="/wiki/Carbamoyl_phosphate" title="Carbamoyl phosphate">carbamoyl phosphate</a> + 2<a href="/wiki/Adenosine_diphosphate" title="Adenosine diphosphate">ADP</a> + <a href="/wiki/Phosphate#Biochemistry_of_phosphates" title="Phosphate">P<sub>i</sub></a></td> <td><a href="/wiki/Carbamoyl_phosphate_synthetase_I" title="Carbamoyl phosphate synthetase I">CPS1</a></td> <td>mitochondria </td></tr> <tr> <th>2 </th> <td><a href="/wiki/Carbamoyl_phosphate" title="Carbamoyl phosphate">carbamoyl phosphate</a> + <a href="/wiki/Ornithine" title="Ornithine">ornithine</a></td> <td><a href="/wiki/Citrulline" title="Citrulline">citrulline</a> + P<sub>i</sub></td> <td><a href="/wiki/Ornithine_transcarbamylase" title="Ornithine transcarbamylase">OTC</a>, zinc, biotin</td> <td>mitochondria </td></tr> <tr> <th>3 </th> <td><a href="/wiki/Citrulline" title="Citrulline">citrulline</a> + <a href="/wiki/Aspartic_acid" title="Aspartic acid">aspartate</a> + <a href="/wiki/Adenosine_triphosphate" title="Adenosine triphosphate">ATP</a></td> <td><a href="/wiki/Arginosuccinic_acid" class="mw-redirect" title="Arginosuccinic acid">argininosuccinate</a> + <a href="/wiki/Adenosine_monophosphate" title="Adenosine monophosphate">AMP</a> + <a href="/wiki/Pyrophosphate" title="Pyrophosphate">PP<sub>i</sub></a></td> <td><a href="/wiki/Argininosuccinate_synthetase" class="mw-redirect" title="Argininosuccinate synthetase">ASS</a></td> <td>cytosol </td></tr> <tr> <th>4 </th> <td><a href="/wiki/Arginosuccinic_acid" class="mw-redirect" title="Arginosuccinic acid">argininosuccinate</a></td> <td><a href="/wiki/Arginine" title="Arginine">arginine</a> + <a href="/wiki/Fumarate" class="mw-redirect" title="Fumarate">fumarate</a></td> <td><a href="/wiki/Argininosuccinate_lyase" title="Argininosuccinate lyase">ASL</a></td> <td>cytosol </td></tr> <tr> <th>5 </th> <td><a href="/wiki/Arginine" title="Arginine">arginine</a> + H<sub>2</sub>O</td> <td><a href="/wiki/Ornithine" title="Ornithine">ornithine</a> + <a href="/wiki/Urea" title="Urea">urea</a></td> <td><a href="/wiki/Arginase_1" class="mw-redirect" title="Arginase 1">ARG1</a>, manganese</td> <td>cytosol </td></tr></tbody></table> <blockquote> <dl><dd><dl><dd><b>The reactions of the urea cycle</b></dd></dl></dd></dl> <figure class="mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:Urea_cycle.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/be/Urea_cycle.svg/480px-Urea_cycle.svg.png" decoding="async" width="480" height="725" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/be/Urea_cycle.svg/720px-Urea_cycle.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/be/Urea_cycle.svg/960px-Urea_cycle.svg.png 2x" data-file-width="620" data-file-height="936" /></a><figcaption></figcaption></figure> <p>1 <small>L</small>-<a href="/wiki/Ornithine" title="Ornithine">ornithine</a><br />2 <a href="/wiki/Carbamoyl_phosphate" title="Carbamoyl phosphate">carbamoyl phosphate</a><br />3 <small>L</small>-<a href="/wiki/Citrulline" title="Citrulline">citrulline</a><br />4 <a href="/wiki/Argininosuccinate" class="mw-redirect" title="Argininosuccinate">argininosuccinate</a><br />5 <a href="/wiki/Fumarate" class="mw-redirect" title="Fumarate">fumarate</a><br />6 <small>L</small>-<a href="/wiki/Arginine" title="Arginine">arginine</a><br />7 <a href="/wiki/Urea" title="Urea">urea</a><br /> <small>L</small>-Asp <small>L</small>-<a href="/wiki/Aspartate" class="mw-redirect" title="Aspartate">aspartate</a><br />CPS-1 <a href="/wiki/Carbamoyl_phosphate_synthetase_I" title="Carbamoyl phosphate synthetase I">carbamoyl phosphate synthetase I</a><br />OTC <a href="/wiki/Ornithine_transcarbamoylase" class="mw-redirect" title="Ornithine transcarbamoylase">Ornithine transcarbamoylase</a><br />ASS <a href="/wiki/Argininosuccinate_synthetase" class="mw-redirect" title="Argininosuccinate synthetase">argininosuccinate synthetase</a><br />ASL <a href="/wiki/Argininosuccinate_lyase" title="Argininosuccinate lyase">argininosuccinate lyase</a><br />ARG1 <a href="/wiki/Arginase" title="Arginase">arginase 1</a> </p> </blockquote> <div style="clear:both;" class=""></div> <div class="mw-heading mw-heading3"><h3 id="First_reaction:_entering_the_urea_cycle">First reaction: entering the urea cycle</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Urea_cycle&action=edit&section=3" title="Edit section: First reaction: entering the urea cycle"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Before the urea cycle begins ammonia is converted to carbamoyl phosphate. The reaction is catalyzed by <a href="/wiki/Carbamoyl_phosphate_synthetase_I" title="Carbamoyl phosphate synthetase I">carbamoyl phosphate synthetase I</a> and requires the use of two <a href="/wiki/Adenosine_triphosphate" title="Adenosine triphosphate">ATP</a> molecules.<sup id="cite_ref-:0_1-3" class="reference"><a href="#cite_note-:0-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> The carbamoyl phosphate then enters the urea cycle. </p> <div class="mw-heading mw-heading3"><h3 id="Steps_of_the_urea_cycle">Steps of the urea cycle</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Urea_cycle&action=edit&section=4" title="Edit section: Steps of the urea cycle"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ol><li>Carbamoyl phosphate is converted to <a href="/wiki/Citrulline" title="Citrulline">citrulline</a>. With catalysis by <a href="/wiki/Ornithine_transcarbamylase" title="Ornithine transcarbamylase">ornithine transcarbamylase</a>, the carbamoyl phosphate group is donated to ornithine and releases a phosphate group.<sup id="cite_ref-:0_1-4" class="reference"><a href="#cite_note-:0-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup></li> <li>A <a href="/wiki/Condensation_reaction" title="Condensation reaction">condensation reaction</a> occurs between the amino group of aspartate and the carbonyl group of citrulline to form <a href="/wiki/Argininosuccinic_acid" title="Argininosuccinic acid">argininosuccinate</a>. This reaction is ATP dependent and is catalyzed by <a href="/wiki/Argininosuccinate_synthase" title="Argininosuccinate synthase">argininosuccinate synthetase</a>.<sup id="cite_ref-:0_1-5" class="reference"><a href="#cite_note-:0-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup></li> <li>Argininosuccinate undergoes cleavage by <a href="/wiki/Argininosuccinate_lyase" title="Argininosuccinate lyase">argininosuccinase</a> to form <a href="/wiki/Arginine" title="Arginine">arginine</a> and <a href="/wiki/Fumarate" class="mw-redirect" title="Fumarate">fumarate</a>.<sup id="cite_ref-:0_1-6" class="reference"><a href="#cite_note-:0-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup></li> <li>Arginine is cleaved by <a href="/wiki/Arginase" title="Arginase">arginase</a> to form urea and ornithine. The ornithine is then transported back to the mitochondria to begin the urea cycle again.<sup id="cite_ref-:0_1-7" class="reference"><a href="#cite_note-:0-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-:3_7-2" class="reference"><a href="#cite_note-:3-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup></li></ol> <div class="mw-heading mw-heading3"><h3 id="Overall_reaction_equation">Overall reaction equation</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Urea_cycle&action=edit&section=5" title="Edit section: Overall reaction equation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In the first reaction, <span class="chemf nowrap">NH<span class="nowrap"><span style="display:inline-block;margin-bottom:-0.3em;vertical-align:-0.4em;line-height:1em;font-size:80%;text-align:left"><sup style="font-size:inherit;line-height:inherit;vertical-align:baseline">+</sup><br /><sub style="font-size:inherit;line-height:inherit;vertical-align:baseline">4</sub></span></span></span> + <span class="chemf nowrap">HCO<span class="nowrap"><span style="display:inline-block;margin-bottom:-0.3em;vertical-align:-0.4em;line-height:1em;font-size:80%;text-align:left"><sup style="font-size:inherit;line-height:inherit;vertical-align:baseline">−</sup><br /><sub style="font-size:inherit;line-height:inherit;vertical-align:baseline">3</sub></span></span></span> is equivalent to <a href="/wiki/Ammonia" title="Ammonia">NH<sub>3</sub></a> + <a href="/wiki/Carbon_dioxide" title="Carbon dioxide">CO<sub>2</sub></a> + <a href="/wiki/Water" title="Water">H<sub>2</sub>O</a>. </p><p>Thus, the overall equation of the urea cycle is: </p> <ul><li><a href="/wiki/Ammonia" title="Ammonia">NH<sub>3</sub></a> + <a href="/wiki/Carbon_dioxide" title="Carbon dioxide">CO<sub>2</sub></a> + <a href="/wiki/Aspartate" class="mw-redirect" title="Aspartate">aspartate</a> + 3 <a href="/wiki/Adenosine_triphosphate" title="Adenosine triphosphate">ATP</a> + 3 <a href="/wiki/Water" title="Water">H<sub>2</sub>O</a> → <a href="/wiki/Urea" title="Urea">urea</a> + <a href="/wiki/Fumarate" class="mw-redirect" title="Fumarate">fumarate</a> + 2 <a href="/wiki/Adenosine_diphosphate" title="Adenosine diphosphate">ADP</a> + 2 <a href="/wiki/Phosphate" title="Phosphate">P<sub>i</sub></a> + <a href="/wiki/Adenosine_monophosphate" title="Adenosine monophosphate">AMP</a> + <a href="/wiki/Pyrophosphate" title="Pyrophosphate">PP<sub>i</sub></a> + <a href="/wiki/Water" title="Water">H<sub>2</sub>O</a></li></ul> <p>Since fumarate is obtained by removing NH<sub>3</sub> from aspartate (by means of reactions 3 and 4), and PP<sub>i</sub> + H<sub>2</sub>O → 2 P<sub>i</sub>, the equation can be simplified as follows: </p> <ul><li>2 <a href="/wiki/Ammonia" title="Ammonia">NH<sub>3</sub></a> + <a href="/wiki/Carbon_dioxide" title="Carbon dioxide">CO<sub>2</sub></a> + 3 <a href="/wiki/Adenosine_triphosphate" title="Adenosine triphosphate">ATP</a> + 3 <a href="/wiki/Water" title="Water">H<sub>2</sub>O</a> → <a href="/wiki/Urea" title="Urea">urea</a> + 2 <a href="/wiki/Adenosine_diphosphate" title="Adenosine diphosphate">ADP</a> + 4 <a href="/wiki/Phosphate" title="Phosphate">P<sub>i</sub></a> + <a href="/wiki/Adenosine_monophosphate" title="Adenosine monophosphate">AMP</a></li></ul> <p>Note that reactions related to the urea cycle also cause the production of 2 <a href="/wiki/NADH" class="mw-redirect" title="NADH">NADH</a>, so the overall reaction releases slightly more energy than it consumes. The NADH is produced in two ways: </p> <ul><li>One NADH molecule is produced by the enzyme <a href="/wiki/Glutamate_dehydrogenase" title="Glutamate dehydrogenase">glutamate dehydrogenase</a> in the conversion of glutamate to ammonium and <a href="/wiki/%CE%91-ketoglutarate" class="mw-redirect" title="Α-ketoglutarate">α-ketoglutarate</a>. <a href="/wiki/Glutamate" class="mw-redirect" title="Glutamate">Glutamate</a> is the non-toxic carrier of amine groups. This provides the ammonium ion used in the initial synthesis of carbamoyl phosphate.</li> <li>The fumarate released in the cytosol is hydrated to <a href="/wiki/Malate" class="mw-redirect" title="Malate">malate</a> by cytosolic <a href="/wiki/Fumarase" title="Fumarase">fumarase</a>. This malate is then oxidized to <a href="/wiki/Oxaloacetate" class="mw-redirect" title="Oxaloacetate">oxaloacetate</a> by cytosolic <a href="/wiki/Malate_dehydrogenase" title="Malate dehydrogenase">malate dehydrogenase</a>, generating a reduced NADH in the cytosol. <a href="/wiki/Oxaloacetate" class="mw-redirect" title="Oxaloacetate">Oxaloacetate</a> is one of the keto acids preferred by <a href="/wiki/Transaminase" title="Transaminase">transaminases</a>, and so will be recycled to <a href="/wiki/Aspartate" class="mw-redirect" title="Aspartate">aspartate</a>, maintaining the flow of nitrogen into the urea cycle.</li></ul> <p>We can summarize this by combining the reactions: </p> <ul><li>CO<sub>2</sub> + <a href="/wiki/Glutamate" class="mw-redirect" title="Glutamate">glutamate</a> + <a href="/wiki/Aspartate" class="mw-redirect" title="Aspartate">aspartate</a> + 3 ATP + 2 NAD<sup>+</sup>+ 3 H<sub>2</sub>O → <a href="/wiki/Urea" title="Urea">urea</a> + <a href="/wiki/%CE%91-ketoglutarate" class="mw-redirect" title="Α-ketoglutarate">α-ketoglutarate</a> + <a href="/wiki/Oxaloacetate" class="mw-redirect" title="Oxaloacetate">oxaloacetate</a> + 2 ADP + 2 P<sub>i</sub> + AMP + PP<sub>i</sub> + 2 NADH</li></ul> <p>The two NADH produced can provide energy for the formation of 5 <a href="/wiki/Adenosine_triphosphate" title="Adenosine triphosphate">ATP</a> (cytosolic NADH provides 2.5 ATP with the malate-aspartate shuttle in human liver cell), a net production of two high-energy phosphate bond for the urea cycle. However, if <a href="/wiki/Gluconeogenesis" title="Gluconeogenesis">gluconeogenesis</a> is underway in the cytosol, the latter reducing equivalent is used to drive the reversal of the <a href="/wiki/GAPDH" class="mw-redirect" title="GAPDH">GAPDH</a> step instead of generating ATP. </p><p>The fate of oxaloacetate is either to produce aspartate via transamination or to be converted to <a href="/wiki/Phosphoenolpyruvic_acid" title="Phosphoenolpyruvic acid">phosphoenolpyruvate</a>, which is a substrate for <a href="/wiki/Gluconeogenesis" title="Gluconeogenesis">gluconeogenesis</a>. </p> <div class="mw-heading mw-heading2"><h2 id="Products_of_the_urea_cycle">Products of the urea cycle</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Urea_cycle&action=edit&section=6" title="Edit section: Products of the urea cycle"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>As stated above many vertebrates use the urea cycle to create urea out of ammonium so that the ammonium does not damage the body. Though this is helpful, there are other effects of the urea cycle. For example: consumption of two ATP, production of urea, generation of H<sup>+</sup>, the combining of <style data-mw-deduplicate="TemplateStyles:r1123817410">.mw-parser-output .template-chem2-su{display:inline-block;font-size:80%;line-height:1;vertical-align:-0.35em}.mw-parser-output .template-chem2-su>span{display:block;text-align:left}.mw-parser-output sub.template-chem2-sub{font-size:80%;vertical-align:-0.35em}.mw-parser-output sup.template-chem2-sup{font-size:80%;vertical-align:0.65em}</style><span class="chemf nowrap">HCO<span class="template-chem2-su"><span>−</span><span>3</span></span></span> and <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1123817410"><span class="chemf nowrap">NH<span class="template-chem2-su"><span>+</span><span>4</span></span></span> to forms where it can be regenerated, and finally the consumption of <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1123817410"><span class="chemf nowrap">NH<span class="template-chem2-su"><span>+</span><span>4</span></span></span>.<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Regulation">Regulation</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Urea_cycle&action=edit&section=7" title="Edit section: Regulation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="N-Acetylglutamic_acid"><i>N</i>-Acetylglutamic acid</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Urea_cycle&action=edit&section=8" title="Edit section: N-Acetylglutamic acid"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The synthesis of carbamoyl phosphate and the urea cycle are dependent on the presence of <a href="/wiki/N-Acetylglutamic_acid" title="N-Acetylglutamic acid"><i>N</i>-acetylglutamic acid</a> (NAcGlu), which <a href="/wiki/Allosterically" class="mw-redirect" title="Allosterically">allosterically</a> activates <a href="/wiki/Carbamoyl_phosphate_synthase" class="mw-redirect" title="Carbamoyl phosphate synthase">CPS1</a>. NAcGlu is an obligate activator of carbamoyl phosphate synthetase.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> Synthesis of NAcGlu by <a href="/wiki/N-Acetylglutamate_synthase" title="N-Acetylglutamate synthase"><i>N</i>-acetylglutamate synthase</a> (NAGS) is stimulated by both Arg, allosteric stimulator of NAGS, and Glu, a product in the transamination reactions and one of NAGS's substrates, both of which are elevated when free <a href="/wiki/Amino_acid" title="Amino acid">amino acids</a> are elevated. So Glu not only is a substrate for NAGS but also serves as an activator for the urea cycle. </p> <div class="mw-heading mw-heading3"><h3 id="Substrate_concentrations">Substrate concentrations</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Urea_cycle&action=edit&section=9" title="Edit section: Substrate concentrations"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The remaining enzymes of the cycle are controlled by the concentrations of their substrates. Thus, inherited deficiencies in cycle enzymes other than <a href="/wiki/Protein:ARG1" class="mw-redirect" title="Protein:ARG1">ARG1</a> do not result in significant decreases in urea production (if any cycle enzyme is entirely missing, death occurs shortly after birth). Rather, the deficient enzyme's substrate builds up, increasing the rate of the deficient reaction to normal. </p><p>The anomalous substrate buildup is not without cost, however. The substrate concentrations become elevated all the way back up the cycle to <span class="chemf nowrap">NH<span class="nowrap"><span style="display:inline-block;margin-bottom:-0.3em;vertical-align:-0.4em;line-height:1em;font-size:80%;text-align:left"><sup style="font-size:inherit;line-height:inherit;vertical-align:baseline">+</sup><br /><sub style="font-size:inherit;line-height:inherit;vertical-align:baseline">4</sub></span></span></span>, resulting in <a href="/wiki/Hyperammonemia" title="Hyperammonemia">hyperammonemia</a> (elevated [<span class="chemf nowrap">NH<span class="nowrap"><span style="display:inline-block;margin-bottom:-0.3em;vertical-align:-0.4em;line-height:1em;font-size:80%;text-align:left"><sup style="font-size:inherit;line-height:inherit;vertical-align:baseline">+</sup><br /><sub style="font-size:inherit;line-height:inherit;vertical-align:baseline">4</sub></span></span></span>]<sub>P</sub>). </p><p>Although the root cause of <span class="chemf nowrap">NH<span class="nowrap"><span style="display:inline-block;margin-bottom:-0.3em;vertical-align:-0.4em;line-height:1em;font-size:80%;text-align:left"><sup style="font-size:inherit;line-height:inherit;vertical-align:baseline">+</sup><br /><sub style="font-size:inherit;line-height:inherit;vertical-align:baseline">4</sub></span></span></span> toxicity is not completely understood, a high [<span class="chemf nowrap">NH<span class="nowrap"><span style="display:inline-block;margin-bottom:-0.3em;vertical-align:-0.4em;line-height:1em;font-size:80%;text-align:left"><sup style="font-size:inherit;line-height:inherit;vertical-align:baseline">+</sup><br /><sub style="font-size:inherit;line-height:inherit;vertical-align:baseline">4</sub></span></span></span>] puts an enormous strain on the <span class="chemf nowrap">NH<span class="nowrap"><span style="display:inline-block;margin-bottom:-0.3em;vertical-align:-0.4em;line-height:1em;font-size:80%;text-align:left"><sup style="font-size:inherit;line-height:inherit;vertical-align:baseline">+</sup><br /><sub style="font-size:inherit;line-height:inherit;vertical-align:baseline">4</sub></span></span></span>-clearing system, especially in the <a href="/wiki/Human_brain" title="Human brain">brain</a> (symptoms of urea cycle enzyme deficiencies include <a href="/wiki/Intellectual_disability" title="Intellectual disability">intellectual disability</a> and <a href="/wiki/Lethargy" title="Lethargy">lethargy</a>). This clearing system involves <a href="/wiki/Protein:GLUD1" class="mw-redirect" title="Protein:GLUD1">GLUD1</a> and <a href="/wiki/Protein:GLUL" class="mw-redirect" title="Protein:GLUL">GLUL</a>, which decrease the <a href="/wiki/2-oxoglutarate" class="mw-redirect" title="2-oxoglutarate">2-oxoglutarate</a> (2OG) and Glu pools. The brain is most sensitive to the depletion of these pools. Depletion of 2OG decreases the rate of <a href="/wiki/TCAC" class="mw-redirect" title="TCAC">TCAC</a>, whereas Glu is both a <a href="/wiki/Neurotransmitter" title="Neurotransmitter">neurotransmitter</a> and a precursor to <a href="/wiki/GABA" title="GABA">GABA</a>, another neurotransmitter. <a rel="nofollow" class="external autonumber" href="http://www.wiley.com/college/math/chem/cg/sales/voet.html">[1]</a><i>(p.734)</i> </p> <div class="mw-heading mw-heading2"><h2 id="Link_with_the_citric_acid_cycle">Link with the citric acid cycle</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Urea_cycle&action=edit&section=10" title="Edit section: Link with the citric acid cycle"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The urea cycle and the <a href="/wiki/Citric_acid_cycle" title="Citric acid cycle">citric acid cycle</a> are independent cycles but are linked. One of the nitrogen atoms in the urea cycle is obtained from the transamination of oxaloacetate to aspartate.<sup id="cite_ref-:1_11-0" class="reference"><a href="#cite_note-:1-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> The fumarate that is produced in step three is also an intermediate in the citric acid cycle and is returned to that cycle.<sup id="cite_ref-:1_11-1" class="reference"><a href="#cite_note-:1-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Urea_cycle_disorders">Urea cycle disorders</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Urea_cycle&action=edit&section=11" title="Edit section: Urea cycle disorders"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Urea cycle disorders are rare and affect about one in 35,000 people in the <a href="/wiki/United_States" title="United States">United States</a>.<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> <a href="/wiki/Genetic_disorder" title="Genetic disorder">Genetic defects</a> in the enzymes involved in the cycle can occur, which usually manifest within a few days after birth.<sup id="cite_ref-:122_5-1" class="reference"><a href="#cite_note-:122-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> The recently born child will typically experience varying bouts of <a href="/wiki/Vomiting" title="Vomiting">vomiting</a> and periods of <a href="/wiki/Lethargy" title="Lethargy">lethargy</a>.<sup id="cite_ref-:122_5-2" class="reference"><a href="#cite_note-:122-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> Ultimately, the infant may go into a <a href="/wiki/Coma" title="Coma">coma</a> and develop <a href="/wiki/Brain_damage" class="mw-redirect" title="Brain damage">brain damage</a>.<sup id="cite_ref-:122_5-3" class="reference"><a href="#cite_note-:122-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> New-borns with UCD are at a much higher risk of complications or death due to untimely <a href="/wiki/Screening_(medicine)" title="Screening (medicine)">screening tests</a> and <a href="/wiki/Medical_error" title="Medical error">misdiagnosed</a> cases. The most common misdiagnosis is <a href="/wiki/Neonatal_sepsis" title="Neonatal sepsis">neonatal sepsis</a>. Signs of UCD can be present within the first 2 to 3 days of life, but the present method to get confirmation by test results can take too long.<sup id="cite_ref-:5_13-0" class="reference"><a href="#cite_note-:5-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> This can potentially cause complications such as coma or death.<sup id="cite_ref-:5_13-1" class="reference"><a href="#cite_note-:5-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> </p><p>Urea cycle disorders may also be diagnosed in adults, and symptoms may include <a href="/wiki/Delirium" title="Delirium">delirium</a> episodes, <a href="/wiki/Lethargy" title="Lethargy">lethargy</a>, and symptoms similar to that of a <a href="/wiki/Stroke" title="Stroke">stroke</a>.<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> On top of these symptoms, if the urea cycle begins to malfunction in the <a href="/wiki/Liver" title="Liver">liver</a>, the patient may develop <a href="/wiki/Cirrhosis" title="Cirrhosis">cirrhosis</a>.<sup id="cite_ref-:6_15-0" class="reference"><a href="#cite_note-:6-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> This can also lead to <a href="/wiki/Sarcopenia" title="Sarcopenia">sarcopenia</a> (the loss of muscle mass).<sup id="cite_ref-:6_15-1" class="reference"><a href="#cite_note-:6-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> Mutations lead to deficiencies of the various enzymes and transporters involved in the urea cycle, and cause urea cycle disorders.<sup id="cite_ref-:0_1-8" class="reference"><a href="#cite_note-:0-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> If individuals with a defect in any of the six enzymes used in the cycle ingest <a href="/wiki/Amino_acid" title="Amino acid">amino acids</a> beyond what is necessary for the minimum daily requirements, then the ammonia that is produced will not be able to be converted to urea. These individuals can experience <a href="/wiki/Hyperammonemia" title="Hyperammonemia">hyperammonemia</a>, or the build-up of a cycle intermediate. </p> <div class="mw-heading mw-heading3"><h3 id="Individual_disorders">Individual disorders</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Urea_cycle&action=edit&section=12" title="Edit section: Individual disorders"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/N-Acetylglutamate_synthase_deficiency" title="N-Acetylglutamate synthase deficiency">N-Acetylglutamate synthase (NAGS) deficiency</a></li> <li><a href="/wiki/Carbamoyl_phosphate_synthetase_I_deficiency" title="Carbamoyl phosphate synthetase I deficiency">Carbamoyl phosphate synthetase (CPS) deficiency</a></li> <li><a href="/wiki/Ornithine_transcarbamoylase_deficiency" class="mw-redirect" title="Ornithine transcarbamoylase deficiency">Ornithine transcarbamoylase (OTC) deficiency</a></li> <li><a href="/wiki/Citrullinemia" title="Citrullinemia">Citrullinemia type I</a> (Deficiency of argininosuccinic acid synthase)</li> <li><a href="/wiki/Argininosuccinic_aciduria" title="Argininosuccinic aciduria">Argininosuccinic aciduria</a> (Deficiency of argininosuccinic acid lyase)</li> <li><a href="/wiki/Argininemia" title="Argininemia">Argininemia</a> (Deficiency of arginase)</li> <li><a href="/wiki/Hyperornithinemia,_hyperammonemia,_homocitrullinuria_syndrome" class="mw-redirect" title="Hyperornithinemia, hyperammonemia, homocitrullinuria syndrome">Hyperornithinemia, hyperammonemia, homocitrullinuria (HHH) syndrome</a> (Deficiency of the mitochondrial ornithine transporter)<sup id="cite_ref-:4_8-1" class="reference"><a href="#cite_note-:4-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup></li></ul> <p>All urea cycle defects, except OTC deficiency, are inherited in an <a href="/wiki/Autosomal_recessive" class="mw-redirect" title="Autosomal recessive">autosomal recessive</a> manner. OTC deficiency is inherited as an <a href="/wiki/X-linked_recessive" class="mw-redirect" title="X-linked recessive">X-linked recessive</a> disorder, although some females can show symptoms. Most urea cycle disorders are associated with <a href="/wiki/Hyperammonemia" title="Hyperammonemia">hyperammonemia</a>, however argininemia and some forms of argininosuccinic aciduria do not present with elevated ammonia. </p> <div class="mw-heading mw-heading2"><h2 id="Additional_images">Additional images</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Urea_cycle&action=edit&section=13" title="Edit section: Additional images"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul class="gallery mw-gallery-traditional"> <li class="gallerybox" style="width: 155px"> <div class="thumb" style="width: 150px; height: 150px;"><span typeof="mw:File"><a href="/wiki/File:Urea-Cycle_scheme_2006-01.svg" class="mw-file-description" title="Urea cycle."><img alt="Urea cycle." src="//upload.wikimedia.org/wikipedia/commons/thumb/e/eb/Urea-Cycle_scheme_2006-01.svg/120px-Urea-Cycle_scheme_2006-01.svg.png" decoding="async" width="120" height="90" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/eb/Urea-Cycle_scheme_2006-01.svg/180px-Urea-Cycle_scheme_2006-01.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/eb/Urea-Cycle_scheme_2006-01.svg/240px-Urea-Cycle_scheme_2006-01.svg.png 2x" data-file-width="800" data-file-height="600" /></a></span></div> <div class="gallerytext">Urea cycle.</div> </li> <li class="gallerybox" style="width: 155px"> <div class="thumb" style="width: 150px; height: 150px;"><span typeof="mw:File"><a href="/wiki/File:Urea_cycle_2.png" class="mw-file-description" title="Urea cycle colored."><img alt="Urea cycle colored." src="//upload.wikimedia.org/wikipedia/commons/thumb/5/51/Urea_cycle_2.png/104px-Urea_cycle_2.png" decoding="async" width="104" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/51/Urea_cycle_2.png/156px-Urea_cycle_2.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/51/Urea_cycle_2.png/208px-Urea_cycle_2.png 2x" data-file-width="623" data-file-height="718" /></a></span></div> <div class="gallerytext">Urea cycle colored.</div> </li> </ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Urea_cycle&action=edit&section=14" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-:0-1"><span class="mw-cite-backlink">^ <a href="#cite_ref-:0_1-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:0_1-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-:0_1-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-:0_1-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-:0_1-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-:0_1-5"><sup><i><b>f</b></i></sup></a> <a href="#cite_ref-:0_1-6"><sup><i><b>g</b></i></sup></a> <a href="#cite_ref-:0_1-7"><sup><i><b>h</b></i></sup></a> <a href="#cite_ref-:0_1-8"><sup><i><b>i</b></i></sup></a></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFCox2013" class="citation book cs1">Cox, Michael (2013-01-01). <i>Lehninger Principles of Biochemistry</i>. Freeman. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9781429234146" title="Special:BookSources/9781429234146"><bdi>9781429234146</bdi></a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/901647690">901647690</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Lehninger+Principles+of+Biochemistry&rft.pub=Freeman&rft.date=2013-01-01&rft_id=info%3Aoclcnum%2F901647690&rft.isbn=9781429234146&rft.aulast=Cox&rft.aufirst=Michael&rfr_id=info%3Asid%2Fen.wikipedia.org%3AUrea+cycle" class="Z3988"></span></span> </li> <li id="cite_note-Krebs1932a-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-Krebs1932a_2-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKrebsHenseleit1932" class="citation journal cs1"><a href="/wiki/Hans_Krebs_(biochemist)" title="Hans Krebs (biochemist)">Krebs, Hans Adolf</a>; <a href="/wiki/Kurt_Henseleit" title="Kurt Henseleit">Henseleit, Kurt</a> (1932). "Untersuchungen über die Harnstoffbildung im Tierkörper". <i>Klinische Wochenschrift</i>. <b>11</b> (18): 757–759. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2Fbf01757657">10.1007/bf01757657</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Klinische+Wochenschrift&rft.atitle=Untersuchungen+%C3%BCber+die+Harnstoffbildung+im+Tierk%C3%B6rper&rft.volume=11&rft.issue=18&rft.pages=757-759&rft.date=1932&rft_id=info%3Adoi%2F10.1007%2Fbf01757657&rft.aulast=Krebs&rft.aufirst=Hans+Adolf&rft.au=Henseleit%2C+Kurt&rfr_id=info%3Asid%2Fen.wikipedia.org%3AUrea+cycle" class="Z3988"></span></span> </li> <li id="cite_note-Krebs1932b-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-Krebs1932b_3-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKrebsHenseleit1932" class="citation journal cs1"><a href="/wiki/Hans_Krebs_(biochemist)" title="Hans Krebs (biochemist)">Krebs, Hans Adolf</a>; <a href="/wiki/Kurt_Henseleit" title="Kurt Henseleit">Henseleit, Kurt</a> (1932). "Untersuchungen über die Harnstoffbildung im Tierkörper. II". <i>Klinische Wochenschrift</i>. <b>11</b> (27): 1137–1139. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2FBF01758220">10.1007/BF01758220</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Klinische+Wochenschrift&rft.atitle=Untersuchungen+%C3%BCber+die+Harnstoffbildung+im+Tierk%C3%B6rper.+II&rft.volume=11&rft.issue=27&rft.pages=1137-1139&rft.date=1932&rft_id=info%3Adoi%2F10.1007%2FBF01758220&rft.aulast=Krebs&rft.aufirst=Hans+Adolf&rft.au=Henseleit%2C+Kurt&rfr_id=info%3Asid%2Fen.wikipedia.org%3AUrea+cycle" class="Z3988"></span></span> </li> <li id="cite_note-Krebs1932c-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-Krebs1932c_4-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKrebsHenseleit1932" class="citation journal cs1"><a href="/wiki/Hans_Krebs_(biochemist)" title="Hans Krebs (biochemist)">Krebs, Hans Adolf</a>; <a href="/wiki/Kurt_Henseleit" title="Kurt Henseleit">Henseleit, Kurt</a> (1932). "Untersuchungen über die Harnstoffbildung im Tierkörper". <i>Hoppe-Seyler's Zeitschrift für physiologische Chemie</i>. <b>210</b> (1–2): 33–66. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1515%2Fbchm2.1932.210.1-2.33">10.1515/bchm2.1932.210.1-2.33</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Hoppe-Seyler%27s+Zeitschrift+f%C3%BCr+physiologische+Chemie&rft.atitle=Untersuchungen+%C3%BCber+die+Harnstoffbildung+im+Tierk%C3%B6rper&rft.volume=210&rft.issue=1%E2%80%932&rft.pages=33-66&rft.date=1932&rft_id=info%3Adoi%2F10.1515%2Fbchm2.1932.210.1-2.33&rft.aulast=Krebs&rft.aufirst=Hans+Adolf&rft.au=Henseleit%2C+Kurt&rfr_id=info%3Asid%2Fen.wikipedia.org%3AUrea+cycle" class="Z3988"></span></span> </li> <li id="cite_note-:122-5"><span class="mw-cite-backlink">^ <a href="#cite_ref-:122_5-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:122_5-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-:122_5-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-:122_5-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFTymoczkoBergStryer2013" class="citation book cs1">Tymoczko, John L.; Berg, Jeremy M.; Stryer, Lubert (2013). <i>BIOCHEMISTRY A Short Course</i>. W.H. 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title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Biomarkers+in+Inborn+Errors+of+Metabolism&rft.atitle=Chapter+5%3A+Urea+cycle+and+other+disorders+of+hyperammonemia&rft.pages=103-123&rft.date=2017-01-01&rft_id=info%3Adoi%2F10.1016%2Fb978-0-12-802896-4.00004-3&rft.isbn=978-0-12-802896-4&rft.aulast=Smith&rft.aufirst=L.+D.&rft.au=Garg%2C+U.&rft_id=http%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2FB9780128028964000043&rfr_id=info%3Asid%2Fen.wikipedia.org%3AUrea+cycle" class="Z3988"></span></span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Urea_cycle&action=edit&section=15" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a rel="nofollow" class="external text" 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src="//upload.wikimedia.org/wikipedia/commons/thumb/4/41/Metabolic_Metro_Map_%28no_legends%29.svg/800px-Metabolic_Metro_Map_%28no_legends%29.svg.png" decoding="async" width="800" height="600" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/41/Metabolic_Metro_Map_%28no_legends%29.svg/1200px-Metabolic_Metro_Map_%28no_legends%29.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/41/Metabolic_Metro_Map_%28no_legends%29.svg/1600px-Metabolic_Metro_Map_%28no_legends%29.svg.png 2x" data-file-width="1260" data-file-height="945" /></a></span> </div> <div style="text-align:center; font-size:8px; line-height:110%"> <div style="background-color:transparent; color:black"><div id="annotation_225x150" style="position:absolute; left:225px; top:150px; font-size:15px; font-size:15; line-height:17px;"><span style="background-color:; color:inherit;"> <i><a href="/wiki/Carbon_fixation" class="mw-redirect" title="Carbon fixation"><span style="color:#bc00bc;">Carbon<br />fixation</span></a></i> </span></div> <div id="annotation_135x185" style="position:absolute; left:135px; top:185px; font-size:15px; font-size:15; line-height:17px;"><span style="background-color:; color:inherit;"> <i><a href="/wiki/Photorespiration" title="Photorespiration"><span style="color:#5400a9;">Photo-<br />respiration</span></a></i> </span></div> <div id="annotation_395x140" style="position:absolute; left:395px; top:140px; font-size:15px; font-size:15; line-height:17px;"><span style="background-color:; color:inherit;"> <i><a href="/wiki/Pentose_phosphate_pathway" title="Pentose phosphate pathway"><span style="color:#bc00bc;">Pentose<br />phosphate<br />pathway</span></a></i> </span></div> <div id="annotation_215x340" style="position:absolute; left:215px; top:340px; font-size:15px; font-size:15; line-height:17px;"><span style="background-color:; color:inherit;"> <i><a href="/wiki/Citric_acid_cycle" title="Citric acid cycle"><span style="color:#edb500;">Citric<br />acid cycle</span></a></i> </span></div> <div id="annotation_365x505" style="position:absolute; left:365px; top:505px; font-size:15px; font-size:15; line-height:17px;"><span style="background-color:; color:inherit;"> <i><a href="/wiki/Glyoxylate_cycle" title="Glyoxylate cycle"><span style="color:#edb500;">Glyoxylate<br />cycle</span></a></i> </span></div> <div id="annotation_125x398" style="position:absolute; left:125px; top:398px; font-size:15px; font-size:15; line-height:17px;"><span style="background-color:; color:inherit;"> <i><a class="mw-selflink selflink"><span style="color:#89dd00;">Urea<br />cycle</span></a></i> </span></div> <div id="annotation_495x260" style="position:absolute; left:495px; top:260px; font-size:15px; font-size:15; line-height:17px;"><span style="background-color:; color:inherit;"> <i><a href="/wiki/Fatty_acid_synthesis" title="Fatty acid synthesis"><span style="color:#00d300;">Fatty<br />acid<br />synthesis</span></a></i> </span></div> <div id="annotation_495x335" style="position:absolute; left:495px; top:335px; font-size:15px; font-size:15; line-height:17px;"><span style="background-color:; color:inherit;"> <i><a href="/wiki/Fatty_acid_synthesis" title="Fatty acid synthesis"><span style="color:#00d300;">Fatty<br />acid<br />elongation</span></a></i> </span></div> <div id="annotation_497x425" style="position:absolute; left:497px; top:425px; font-size:15px; font-size:15; line-height:17px;"><span style="background-color:; color:inherit;"> <i><a href="/wiki/Beta_oxidation" title="Beta oxidation"><span style="color:#ff66cc;">Beta<br />oxidation</span></a></i> </span></div> <div id="annotation_495x495" style="position:absolute; left:495px; top:495px; font-size:12px; font-size:12; line-height:14px;"><span style="background-color:; color:inherit;"> <i><a href="/wiki/Beta_oxidation#Peroxisomal_beta-oxidation" title="Beta oxidation"><span style="color:#ff66cc;">Peroxisomal</span></a></i> </span></div> <div id="annotation_497x510" style="position:absolute; left:497px; top:510px; font-size:15px; font-size:15; line-height:17px;"><span style="background-color:; color:inherit;"> <i><a href="/wiki/Beta_oxidation#Peroxisomal_beta-oxidation" title="Beta oxidation"><span style="color:#ff66cc;">beta<br />oxidation</span></a></i> </span></div> <p><br /> </p> <div id="annotation_295x42" style="position:absolute; left:295px; top:42px; font-size:9px; font-size:9; line-height:11px; text-align:right;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Glycogenolysis" title="Glycogenolysis"><span style="color:#8a2c2c;">Glyco-<br />genolysis</span></a></b></i> </span></div> <div id="annotation_280x80" style="position:absolute; left:280px; top:80px; font-size:9px; font-size:9; line-height:11px; text-align:left;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Glycogenesis" title="Glycogenesis"><span style="color:#2e427e;">Glyco-<br />genesis</span></a></b></i> </span></div> <div id="annotation_360x160" style="position:absolute; left:360px; top:160px; font-size:9px; font-size:9; line-height:11px; text-align:left;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Glycolysis" title="Glycolysis"><span style="color:#ea0000;">Glyco-<br />lysis</span></a></b></i> </span></div> <div id="annotation_300x160" style="position:absolute; left:300px; top:160px; font-size:9px; font-size:9; line-height:11px; text-align:right;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Gluconeogenesis" title="Gluconeogenesis"><span style="color:#0033cc;">Gluconeo-<br />genesis</span></a></b></i> </span></div> <div id="annotation_310x332" style="position:absolute; left:310px; top:332px; font-size:9px; font-size:9; line-height:11px; text-align:right;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Pyruvate_dehydrogenase" title="Pyruvate dehydrogenase"><span style="color:#ea6000;">Pyruvate<br />decarb-<br />oxylation</span></a></b></i> </span></div> <div id="annotation_365x335" style="position:absolute; left:365px; top:335px; font-size:9px; font-size:9; line-height:11px;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Lactic_acid_fermentation" title="Lactic acid fermentation"><span style="color:#d47ff0;">Fermentation</span></a></b></i> </span></div> <div id="annotation_325x430" style="position:absolute; left:325px; top:430px; font-size:9px; font-size:9; line-height:11px; text-align:right;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Ketone_bodies" title="Ketone bodies"><span style="color:#e06c1f;">Keto-<br />lysis</span></a></b></i> </span></div> <div id="annotation_365x430" style="position:absolute; left:365px; top:430px; font-size:9px; font-size:9; line-height:11px; text-align:left;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Ketogenesis" title="Ketogenesis"><span style="color:#5f8216;">Keto-<br />genesis</span></a></b></i> </span></div> <div id="annotation_195x470" style="position:absolute; left:195px; top:470px; font-size:9px; font-size:9; line-height:11px; text-align:left;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Gluconeogenesis" title="Gluconeogenesis"><span style="color:#0033cc;">feeders to<br />gluconeo-<br />genesis</span></a></b></i> </span></div> <div id="annotation_225x230" style="position:absolute; left:225px; top:230px; font-size:9px; font-size:9; line-height:11px; text-align:right;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Carbon_fixation#Carbon_concentrating_mechanisms" class="mw-redirect" title="Carbon fixation"><span style="color:#9373d3;">Direct / C4 / CAM<br />carbon intake</span></a></b></i> </span></div> <div id="annotation_125x143" style="position:absolute; left:125px; top:143px; font-size:9px; font-size:9; line-height:11px;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Light-dependent_reactions" title="Light-dependent reactions"><span style="color:#9373d3;">Light reaction</span></a></b></i> </span></div> <div id="annotation_115x355" style="position:absolute; left:115px; top:355px; font-size:9px; font-size:9; line-height:11px;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Oxidative_phosphorylation" title="Oxidative phosphorylation"><span style="color:#c34747;">Oxidative<br />phosphorylation</span></a></b></i> </span></div> <div id="annotation_25x415" style="position:absolute; left:25px; top:415px; font-size:9px; font-size:9; line-height:11px;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Deamination" title="Deamination"><span style="color:#4999c2;">Amino acid<br />deamination</span></a></b></i> </span></div> <div id="annotation_315x288" style="position:absolute; left:315px; top:288px; font-size:9px; font-size:9; line-height:11px;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Fatty_acid_synthesis#Glycolytic_end_products_are_used_in_the_conversion_of_carbohydrates_into_fatty_acids" title="Fatty acid synthesis"><span style="color:#00d300;">Citrate<br />shuttle</span></a></b></i> </span></div> <div id="annotation_590x415" style="position:absolute; left:590px; top:415px; font-size:9px; font-size:9; line-height:11px; text-align:left;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Lipogenesis" title="Lipogenesis"><span style="color:#00d300;">Lipogenesis</span></a></b></i> </span></div> <div id="annotation_590x455" style="position:absolute; left:590px; top:455px; font-size:9px; font-size:9; line-height:11px; text-align:left;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Lipolysis" title="Lipolysis"><span style="color:#ff66cc;">Lipolysis</span></a></b></i> </span></div> <div id="annotation_585x260" style="position:absolute; left:585px; top:260px; font-size:9px; font-size:9; line-height:11px;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Steroid#Steroidogenesis" title="Steroid"><span style="color:#0099cc;">Steroidogenesis</span></a></b></i> </span></div> <div id="annotation_470x235" style="position:absolute; left:470px; top:235px; font-size:9px; font-size:9; line-height:11px;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Mevalonate_pathway" title="Mevalonate pathway"><span style="color:#0099cc;">MVA pathway</span></a></b></i> </span></div> <div id="annotation_460x210" style="position:absolute; left:460px; top:210px; font-size:9px; font-size:9; line-height:11px;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Non-mevalonate_pathway" title="Non-mevalonate pathway"><span style="color:#af753a;">MEP pathway</span></a></b></i> </span></div> <div id="annotation_487x153" style="position:absolute; left:487px; top:153px; font-size:9px; font-size:9; line-height:11px;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Shikimate_pathway" title="Shikimate pathway"><span style="color:#00cc99;">Shikimate<br />pathway</span></a></b></i> </span></div> <div id="annotation_555x105" style="position:absolute; left:555px; top:105px; font-size:9px; font-size:9; line-height:11px;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Transcription_(genetics)" class="mw-redirect" title="Transcription (genetics)"><span style="color:#79793d;">Transcription &</span></a><br /><a href="/wiki/DNA_replication" title="DNA replication"><span style="color:#79793d;">replication</span></a></b></i> </span></div> <div id="annotation_600x83" style="position:absolute; left:600px; top:83px; font-size:9px; font-size:9; line-height:11px;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Translation_(biology)" title="Translation (biology)"><span style="color:#79793d;">Translation</span></a></b></i> </span></div> <div id="annotation_600x57" style="position:absolute; left:600px; top:57px; font-size:9px; font-size:9; line-height:11px;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Proteolysis" title="Proteolysis"><span style="color:#6666cc;">Proteolysis</span></a></b></i> </span></div> <div id="annotation_687x55" style="position:absolute; left:687px; top:55px; font-size:9px; font-size:9; line-height:11px;"><span style="background-color:; color:inherit;"> <i><b><a href="/wiki/Glycosylation" title="Glycosylation"><span style="color:#79793d;">Glycosyl-<br />ation</span></a></b></i> </span></div> <p><br /> </p> <div id="annotation_210x38" style="position:absolute; left:210px; top:38px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Sugar_acid" title="Sugar acid">Sugar<br />acids</a> </span></div> <div id="annotation_240x38" style="position:absolute; left:240px; top:38px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Disaccharide" title="Disaccharide">Double</a>/<a href="/wiki/Polysaccharide" title="Polysaccharide">multiple<br />sugars</a> & <a href="/wiki/Glycan" title="Glycan">glycans</a> </span></div> <div id="annotation_340x38" style="position:absolute; left:340px; top:38px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Monosaccharide" title="Monosaccharide">Simple<br />sugars</a> </span></div> <div id="annotation_380x45" style="position:absolute; left:380px; top:45px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Inositol_phosphate" title="Inositol phosphate">Inositol-P</a> </span></div> <div id="annotation_160x90" style="position:absolute; left:160px; top:90px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Amino_sugar" title="Amino sugar">Amino sugars</a><br />& <a href="/wiki/Sialic_acid" title="Sialic acid">sialic acids</a> </span></div> <div id="annotation_245x120" style="position:absolute; left:245px; top:120px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Nucleotide_sugar" title="Nucleotide sugar">Nucleotide sugars</a> </span></div> <div id="annotation_365x105" style="position:absolute; left:365px; top:105px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Glucose_6-phosphate" title="Glucose 6-phosphate">Hexose-P</a> </span></div> <div id="annotation_315x180" style="position:absolute; left:315px; top:180px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Glyceraldehyde_3-phosphate" title="Glyceraldehyde 3-phosphate">Triose-P</a> </span></div> <div id="annotation_305x240" style="position:absolute; left:305px; top:240px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Glycerol" title="Glycerol">Glycerol</a> </span></div> <div id="annotation_300x260" style="position:absolute; left:300px; top:260px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Phosphoglycerate" title="Phosphoglycerate">P-glycerates</a> </span></div> <div id="annotation_425x110" style="position:absolute; left:425px; top:110px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Ribose_5-phosphate" title="Ribose 5-phosphate">Pentose-P</a> </span></div> <div id="annotation_470x190" style="position:absolute; left:470px; top:190px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Erythrose_4-phosphate" title="Erythrose 4-phosphate">Tetrose-P</a> </span></div> <div id="annotation_410x440" style="position:absolute; left:410px; top:440px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Propionyl-CoA" title="Propionyl-CoA">Propionyl<br />-CoA</a> </span></div> <div id="annotation_310x495" style="position:absolute; left:310px; top:495px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Succinic_acid" title="Succinic acid">Succinate</a> </span></div> <div id="annotation_455x530" style="position:absolute; left:455px; top:530px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Acetyl-CoA" title="Acetyl-CoA">Acetyl<br />-CoA</a> </span></div> <div id="annotation_150x155" style="position:absolute; left:150px; top:155px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Ribose_5-phosphate" title="Ribose 5-phosphate">Pentose-P</a> </span></div> <div id="annotation_230x210" style="position:absolute; left:230px; top:210px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Phosphoglycerate" title="Phosphoglycerate">P-glycerates</a> </span></div> <div id="annotation_85x180" style="position:absolute; left:85px; top:180px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Glyoxylic_acid" title="Glyoxylic acid">Glyoxylate</a> </span></div> <div id="annotation_65x152" style="position:absolute; left:65px; top:152px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Photosystem" title="Photosystem">Photosystems</a> </span></div> <div id="annotation_320x310" style="position:absolute; left:320px; top:310px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Pyruvic_acid" title="Pyruvic acid">Pyruvate</a> </span></div> <div id="annotation_410x308" style="position:absolute; left:410px; top:308px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Lactic_acid" title="Lactic acid">Lactate</a> </span></div> <div id="annotation_365x345" style="position:absolute; left:365px; top:345px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Acetyl-CoA" title="Acetyl-CoA">Acetyl<br />-CoA</a> </span></div> <div id="annotation_295x380" style="position:absolute; left:295px; top:380px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Citric_acid" title="Citric acid">Citrate</a> </span></div> <div id="annotation_270x300" style="position:absolute; left:270px; top:300px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Oxaloacetic_acid" title="Oxaloacetic acid">Oxalo-<br />acetate</a> </span></div> <div id="annotation_200x310" style="position:absolute; left:200px; top:310px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Malic_acid" title="Malic acid">Malate</a> </span></div> <div id="annotation_195x405" style="position:absolute; left:195px; top:405px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Succinyl-CoA" title="Succinyl-CoA">Succinyl<br />-CoA</a> </span></div> <div id="annotation_275x405" style="position:absolute; left:275px; top:405px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Alpha-Ketoglutaric_acid" class="mw-redirect" title="Alpha-Ketoglutaric acid">α-Keto-<br />glutarate</a> </span></div> <div id="annotation_370x455" style="position:absolute; left:370px; top:455px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Ketone_bodies" title="Ketone bodies">Ketone<br />bodies</a> </span></div> <div id="annotation_70x365" style="position:absolute; left:70px; top:365px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Electron_transport_chain" title="Electron transport chain">Respiratory<br />chain</a> </span></div> <div id="annotation_370x265" style="position:absolute; left:370px; top:265px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Serine" title="Serine">Serine group</a> </span></div> <div id="annotation_395x290" style="position:absolute; left:395px; top:290px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Alanine" title="Alanine">Alanine</a> </span></div> <div id="annotation_415x345" style="position:absolute; left:415px; top:345px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Branched-chain_amino_acid" title="Branched-chain amino acid">Branched-chain<br />amino acids</a> </span></div> <div id="annotation_275x275" style="position:absolute; left:275px; top:275px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Aspartic_acid" title="Aspartic acid">Aspartate<br />group</a> </span></div> <div id="annotation_180x250" style="position:absolute; left:180px; top:250px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Homoserine" title="Homoserine">Homoserine<br />group</a><br />& <a href="/wiki/Lysine" title="Lysine">lysine</a> </span></div> <div id="annotation_280x445" style="position:absolute; left:280px; top:445px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Glutamic_acid" title="Glutamic acid">Glutamate<br />group</a><br />& <a href="/wiki/Proline" title="Proline">proline</a> </span></div> <div id="annotation_105x465" style="position:absolute; left:105px; top:465px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Arginine" title="Arginine">Arginine</a> </span></div> <div id="annotation_40x465" style="position:absolute; left:40px; top:465px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Creatine" title="Creatine">Creatine</a><br />& <a href="/wiki/Polyamine" title="Polyamine">polyamines</a> </span></div> <div id="annotation_415x385" style="position:absolute; left:415px; top:385px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Ketogenic_amino_acid" title="Ketogenic amino acid">Ketogenic</a> &<br /><a href="/wiki/Glucogenic_amino_acid" title="Glucogenic amino acid">glucogenic<br />amino acids</a> </span></div> <div id="annotation_550x85" style="position:absolute; left:550px; top:85px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Amino_acid" title="Amino acid">Amino acids</a> </span></div> <div id="annotation_520x190" style="position:absolute; left:520px; top:190px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Shikimic_acid" title="Shikimic acid">Shikimate</a> </span></div> <div id="annotation_635x165" style="position:absolute; left:635px; top:165px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Aromatic_amino_acid" title="Aromatic amino acid">Aromatic amino<br />acids</a> & <a href="/wiki/Histidine" title="Histidine">histidine</a> </span></div> <div id="annotation_158x38" style="position:absolute; left:158px; top:38px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Ascorbate" class="mw-redirect" title="Ascorbate">Ascorbate</a><br />(<a href="/wiki/Vitamin_C" title="Vitamin C">vitamin C</a>) </span></div> <div id="annotation_275x490" style="position:absolute; left:275px; top:490px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Aminolevulinic_acid" title="Aminolevulinic acid">δ-ALA</a> </span></div> <div id="annotation_155x510" style="position:absolute; left:155px; top:510px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Bile_pigment" class="mw-redirect" title="Bile pigment">Bile<br />pigments</a> </span></div> <div id="annotation_210x520" style="position:absolute; left:210px; top:520px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Heme" title="Heme">Hemes</a> </span></div> <div id="annotation_245x585" style="position:absolute; left:245px; top:585px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Cobalamin" class="mw-redirect" title="Cobalamin">Cobalamins</a> (<a href="/wiki/Vitamin_B" class="mw-redirect" title="Vitamin B">vitamin B<sub>12</sub></a>) </span></div> <div id="annotation_425x45" style="position:absolute; left:425px; top:45px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Vitamin_B" class="mw-redirect" title="Vitamin B">Various<br />vitamin Bs</a> </span></div> <div id="annotation_625x300" style="position:absolute; left:625px; top:300px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Calciferol" class="mw-redirect" title="Calciferol">Calciferols</a><br />(<a href="/wiki/Vitamin_D" title="Vitamin D">vitamin D</a>) </span></div> <div id="annotation_725x235" style="position:absolute; left:725px; top:235px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Retinoid" title="Retinoid">Retinoids</a><br />(<a href="/wiki/Vitamin_A" title="Vitamin A">vitamin A</a>) </span></div> <div id="annotation_590x190" style="position:absolute; left:590px; top:190px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Quinone" title="Quinone">Quinones</a> (<a href="/wiki/Vitamin_K" title="Vitamin K">vitamin K</a>)<br />& <a href="/wiki/Tocopherol" title="Tocopherol">tocopherols</a> (<a href="/wiki/Vitamin_E" title="Vitamin E">vitamin E</a>) </span></div> <div id="annotation_665x140" style="position:absolute; left:665px; top:140px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Cofactor_(biochemistry)" title="Cofactor (biochemistry)">Cofactors</a> </span></div> <div id="annotation_745x140" style="position:absolute; left:745px; top:140px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Vitamin" title="Vitamin">Vitamins</a><br />& <a href="/wiki/Metalloprotein" title="Metalloprotein">minerals</a> </span></div> <div id="annotation_720x185" style="position:absolute; left:720px; top:185px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Antioxidant" title="Antioxidant">Antioxidants</a> </span></div> <div id="annotation_490x140" style="position:absolute; left:490px; top:140px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Phosphoribosyl_pyrophosphate" title="Phosphoribosyl pyrophosphate">PRPP</a> </span></div> <div id="annotation_535x140" style="position:absolute; left:535px; top:140px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Nucleotide" title="Nucleotide">Nucleotides</a> </span></div> <div id="annotation_610x140" style="position:absolute; left:610px; top:140px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Nucleic_acid" title="Nucleic acid">Nucleic<br />acids</a> </span></div> <div id="annotation_665x87" style="position:absolute; left:665px; top:87px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Protein" title="Protein">Proteins</a> </span></div> <div id="annotation_710x87" style="position:absolute; left:710px; top:87px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Glycoprotein" title="Glycoprotein">Glycoproteins</a><br />& <a href="/wiki/Proteoglycan" title="Proteoglycan">proteoglycans</a> </span></div> <div id="annotation_280x520" style="position:absolute; left:280px; top:520px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Chlorophyll" title="Chlorophyll">Chlorophylls</a> </span></div> <div id="annotation_410x235" style="position:absolute; left:410px; top:235px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Methylerythritol_phosphate" class="mw-redirect" title="Methylerythritol phosphate">MEP</a> </span></div> <div id="annotation_420x245" style="position:absolute; left:420px; top:245px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Mevalonic_acid" title="Mevalonic acid">MVA</a> </span></div> <div id="annotation_420x260" style="position:absolute; left:420px; top:260px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Acetyl-CoA" title="Acetyl-CoA">Acetyl<br />-CoA</a> </span></div> <div id="annotation_440x330" style="position:absolute; left:440px; top:330px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Polyketide" title="Polyketide">Polyketides</a> </span></div> <div id="annotation_555x230" style="position:absolute; left:555px; top:230px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Isopentenyl_pyrophosphate" title="Isopentenyl pyrophosphate">Terpenoid<br />backbones</a> </span></div> <div id="annotation_625x235" style="position:absolute; left:625px; top:235px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Terpenoid" title="Terpenoid">Terpenoids</a><br />& <a href="/wiki/Carotenoid" title="Carotenoid">carotenoids</a> (<a href="/wiki/Vitamin_A" title="Vitamin A">vitamin A</a>) </span></div> <div id="annotation_640x287" style="position:absolute; left:640px; top:287px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Cholesterol" title="Cholesterol">Cholesterol</a> </span></div> <div id="annotation_720x287" style="position:absolute; left:720px; top:287px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Bile_acid" title="Bile acid">Bile acids</a> </span></div> <div id="annotation_640x330" style="position:absolute; left:640px; top:330px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Glycerophospholipid" title="Glycerophospholipid">Glycero-<br />phospholipids</a> </span></div> <div id="annotation_600x397" style="position:absolute; left:600px; top:397px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Glycerolipid" class="mw-redirect" title="Glycerolipid">Glycerolipids</a> </span></div> <div id="annotation_620x430" style="position:absolute; left:620px; top:430px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Acyl-CoA" title="Acyl-CoA">Acyl-CoA</a> </span></div> <div id="annotation_630x500" style="position:absolute; left:630px; top:500px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Fatty_acid" title="Fatty acid">Fatty<br />acids</a> </span></div> <div id="annotation_720x350" style="position:absolute; left:720px; top:350px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Glycosphingolipid" title="Glycosphingolipid">Glyco-<br />sphingolipids</a> </span></div> <div id="annotation_720x397" style="position:absolute; left:720px; top:397px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Sphingolipid" title="Sphingolipid">Sphingolipids</a> </span></div> <div id="annotation_720x440" style="position:absolute; left:720px; top:440px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Wax" title="Wax">Waxes</a> </span></div> <div id="annotation_680x497" style="position:absolute; left:680px; top:497px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Polyunsaturated_fatty_acid" class="mw-redirect" title="Polyunsaturated fatty acid">Polyunsaturated<br />fatty acids</a> </span></div> <div id="annotation_470x45" style="position:absolute; left:470px; top:45px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Neurotransmitters" class="mw-redirect" title="Neurotransmitters">Neurotransmitters</a><br />& <a href="/wiki/Thyroid_hormone" class="mw-redirect" title="Thyroid hormone">thyroid hormones</a> </span></div> <div id="annotation_705x305" style="position:absolute; left:705px; top:305px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Steroid" title="Steroid">Steroids</a> </span></div> <div id="annotation_587x330" style="position:absolute; left:587px; top:330px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Endocannabinoid_system" title="Endocannabinoid system">Endo-<br />cannabinoids</a> </span></div> <div id="annotation_735x465" style="position:absolute; left:735px; top:465px; line-height:110%;"><span style="background-color:transparent; color:inherit;"> <a href="/wiki/Eicosanoid" title="Eicosanoid">Eicosanoids</a> </span></div></div> </div> </div> </div> </div> </td></tr></tbody></table></div><div class="thumbcaption"><div style="float:left;margin-right:0.5em"><span typeof="mw:File"><span title="The image above contains clickable links"><img alt="The image above contains clickable links" src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e6/Interactive_icon.svg/18px-Interactive_icon.svg.png" decoding="async" width="18" height="27" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e6/Interactive_icon.svg/27px-Interactive_icon.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e6/Interactive_icon.svg/36px-Interactive_icon.svg.png 2x" data-file-width="133" data-file-height="200" /></span></span></div> Major <a href="/wiki/Metabolic_pathway" title="Metabolic pathway">metabolic pathways</a> in <a href="/wiki/Transit_map" title="Transit map">metro-style map</a>. Click any text (name of pathway or metabolites) to link to the corresponding article.<br />Single lines: pathways common to most lifeforms. Double lines: pathways not in humans (occurs in e.g. plants, fungi, prokaryotes). <span class="nowrap"><span typeof="mw:File"><span><img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a0/Metabolic_metro_orange.svg/15px-Metabolic_metro_orange.svg.png" decoding="async" width="15" height="17" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a0/Metabolic_metro_orange.svg/23px-Metabolic_metro_orange.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a0/Metabolic_metro_orange.svg/30px-Metabolic_metro_orange.svg.png 2x" data-file-width="30" data-file-height="34" /></span></span> Orange nodes: <a href="/wiki/Carbohydrate_metabolism" title="Carbohydrate metabolism">carbohydrate metabolism</a>.</span> <span class="nowrap"><span typeof="mw:File"><span><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e7/Metabolic_metro_purple.svg/15px-Metabolic_metro_purple.svg.png" decoding="async" width="15" height="17" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e7/Metabolic_metro_purple.svg/23px-Metabolic_metro_purple.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e7/Metabolic_metro_purple.svg/30px-Metabolic_metro_purple.svg.png 2x" data-file-width="30" data-file-height="34" /></span></span> Violet nodes: <a href="/wiki/Photosynthesis" title="Photosynthesis">photosynthesis</a>.</span> <span class="nowrap"><span typeof="mw:File"><span><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/ba/Metabolic_metro_red.svg/15px-Metabolic_metro_red.svg.png" decoding="async" width="15" height="17" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/ba/Metabolic_metro_red.svg/23px-Metabolic_metro_red.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/ba/Metabolic_metro_red.svg/30px-Metabolic_metro_red.svg.png 2x" data-file-width="30" data-file-height="34" /></span></span> Red nodes: <a href="/wiki/Cellular_respiration" title="Cellular respiration">cellular respiration</a>.</span> <span class="nowrap"><span typeof="mw:File"><span><img src="//upload.wikimedia.org/wikipedia/commons/thumb/d/db/Metabolic_metro_pink.svg/15px-Metabolic_metro_pink.svg.png" decoding="async" width="15" height="17" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/db/Metabolic_metro_pink.svg/23px-Metabolic_metro_pink.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/db/Metabolic_metro_pink.svg/30px-Metabolic_metro_pink.svg.png 2x" data-file-width="30" data-file-height="34" /></span></span> Pink nodes: <a href="/wiki/Cell_signaling" title="Cell signaling">cell signaling</a>.</span> <span class="nowrap"><span typeof="mw:File"><span><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/1b/Metabolic_metro_blue.svg/15px-Metabolic_metro_blue.svg.png" decoding="async" width="15" height="17" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/1b/Metabolic_metro_blue.svg/23px-Metabolic_metro_blue.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/1b/Metabolic_metro_blue.svg/30px-Metabolic_metro_blue.svg.png 2x" data-file-width="30" data-file-height="34" /></span></span> Blue nodes: <a href="/wiki/Amino_acid_metabolism" class="mw-redirect" title="Amino acid metabolism">amino acid metabolism</a>.</span> <span class="nowrap"><span typeof="mw:File"><span><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c8/Metabolic_metro_grey.svg/15px-Metabolic_metro_grey.svg.png" decoding="async" width="15" height="17" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c8/Metabolic_metro_grey.svg/23px-Metabolic_metro_grey.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c8/Metabolic_metro_grey.svg/30px-Metabolic_metro_grey.svg.png 2x" data-file-width="30" data-file-height="34" /></span></span> Grey nodes: <a href="/wiki/Vitamin" title="Vitamin">vitamin</a> and <a href="/wiki/Cofactor_(biochemistry)" title="Cofactor (biochemistry)">cofactor</a> metabolism.</span> <span class="nowrap"><span typeof="mw:File"><span><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/99/Metabolic_metro_brown.svg/15px-Metabolic_metro_brown.svg.png" decoding="async" width="15" height="17" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/99/Metabolic_metro_brown.svg/23px-Metabolic_metro_brown.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/99/Metabolic_metro_brown.svg/30px-Metabolic_metro_brown.svg.png 2x" data-file-width="30" data-file-height="34" /></span></span> Brown nodes: <a href="/wiki/Nucleic_acid_metabolism" title="Nucleic acid metabolism">nucleotide</a> and <a href="/wiki/Protein_metabolism" title="Protein metabolism">protein</a> metabolism.</span> <span class="nowrap"><span typeof="mw:File"><span><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/97/Metabolic_metro_green.svg/15px-Metabolic_metro_green.svg.png" decoding="async" width="15" height="17" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/97/Metabolic_metro_green.svg/23px-Metabolic_metro_green.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/97/Metabolic_metro_green.svg/30px-Metabolic_metro_green.svg.png 2x" data-file-width="30" data-file-height="34" /></span></span> Green nodes: <a href="/wiki/Lipid_metabolism" title="Lipid metabolism">lipid metabolism</a>.</span></div></div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Urea_cycle_Metabolic_Pathway" style="display:table;;padding:3px"><table class="nowraplinks hlist mw-collapsible mw-collapsed navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Urea_cycle" title="Template:Urea cycle"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Urea_cycle" title="Template talk:Urea cycle"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Urea_cycle" title="Special:EditPage/Template:Urea cycle"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Urea_cycle_Metabolic_Pathway" style="font-size:114%;margin:0 4em"><a class="mw-selflink selflink">Urea cycle</a> <a href="/wiki/Metabolic_pathway" title="Metabolic pathway">Metabolic Pathway</a></div></th></tr><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0;border-width:0;"><div style="padding:0"> <table style="width:100%" class="wraplinks"> <tbody><tr> <td> <table border="0" style="font-size:100%;" align="center"> <tbody><tr> <td></td> <td></td> <td><div style="text-align: center; display: inline-block; display: inline-flex; flex-flow: column; flex: 1; vertical-align:top; text-align:right;margin:0 -2em -11px"><div style="width: 100%; display: block; background-color:lightgreen;"> <p style="margin: 0.1em 0.5em;"><a href="/wiki/Carbamoyl_phosphate" title="Carbamoyl phosphate">Carbamoyl phosphate</a></p> </div><div style="margin: auto 0"><span typeof="mw:File"><a href="/wiki/File:Carbamoylphosphat_deprotoniert.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/94/Carbamoylphosphat_deprotoniert.svg/75px-Carbamoylphosphat_deprotoniert.svg.png" decoding="async" width="75" height="45" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/94/Carbamoylphosphat_deprotoniert.svg/113px-Carbamoylphosphat_deprotoniert.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/94/Carbamoylphosphat_deprotoniert.svg/150px-Carbamoylphosphat_deprotoniert.svg.png 2x" data-file-width="197" data-file-height="117" /></a></span></div> </div> </td></tr> <tr style="vertical-align:bottom"> <td> </td> <td><div style="text-align: center; display: inline-block; display: inline-flex; flex-flow: column; flex: 1; vertical-align:top; vertical-align:bottom;margin-bottom:-15px"><div style="width: 100%; display: block; background-color:lightgreen;"> <p style="margin: 0.1em 0.5em;"><small>L</small>-<a href="/wiki/Citrulline" title="Citrulline">citrulline</a></p> </div><div style="margin: auto 0"><span typeof="mw:File"><a href="/wiki/File:L-Citrullin2.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/63/L-Citrullin2.svg/140px-L-Citrullin2.svg.png" decoding="async" width="140" height="51" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/63/L-Citrullin2.svg/210px-L-Citrullin2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/63/L-Citrullin2.svg/280px-L-Citrullin2.svg.png 2x" data-file-width="335" data-file-height="121" /></a></span></div> </div> </td> <td rowspan="3" style="vertical-align: top"><div style="margin:0 auto; width: 65px; text-align:left" class="template-imageflip-vert"><span typeof="mw:File"><a href="/wiki/File:Biochem_reaction_arrow_reverse_YNYN_horiz_med.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/03/Biochem_reaction_arrow_reverse_YNYN_horiz_med.svg/65px-Biochem_reaction_arrow_reverse_YNYN_horiz_med.svg.png" decoding="async" width="65" height="65" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/03/Biochem_reaction_arrow_reverse_YNYN_horiz_med.svg/98px-Biochem_reaction_arrow_reverse_YNYN_horiz_med.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/03/Biochem_reaction_arrow_reverse_YNYN_horiz_med.svg/130px-Biochem_reaction_arrow_reverse_YNYN_horiz_med.svg.png 2x" data-file-width="75" data-file-height="75" /></a></span><br />P<sub>i</sub></div> </td> <td><div style="text-align: center; display: inline-block; display: inline-flex; flex-flow: column; flex: 1; vertical-align:top; margin: 1em 0 -1em;display:flex"><div style="width: 100%; display: block; background-color:lightgreen;"> <p style="margin: 0.1em 0.5em;"><small>L</small>-<a href="/wiki/Ornithine" title="Ornithine">ornithine</a></p> </div><div style="margin: auto 0"><span typeof="mw:File"><a href="/wiki/File:L-Ornithin2.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a2/L-Ornithin2.svg/100px-L-Ornithin2.svg.png" decoding="async" width="100" height="45" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a2/L-Ornithin2.svg/150px-L-Ornithin2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a2/L-Ornithin2.svg/200px-L-Ornithin2.svg.png 2x" data-file-width="266" data-file-height="121" /></a></span></div> </div> </td> <td style="text-align:center;vertical-align:bottom" rowspan="2"><div style="text-align: center; display: inline-block; display: inline-flex; flex-flow: column; flex: 1; vertical-align:top;"><div style="width: 100%; display: block; background-color:lightgreen;"> <p style="margin: 0.1em 0.5em;"><a href="/wiki/Urea" title="Urea">Urea</a></p> </div><div style="margin: auto 0"><span typeof="mw:File"><a href="/wiki/File:Harnstoff.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/3d/Harnstoff.svg/65px-Harnstoff.svg.png" decoding="async" width="65" height="41" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/3d/Harnstoff.svg/98px-Harnstoff.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/3d/Harnstoff.svg/130px-Harnstoff.svg.png 2x" data-file-width="512" data-file-height="325" /></a></span></div> </div> </td></tr> <tr> <td style="text-align:right;"><div style="text-align: center; display: inline-block; display: inline-flex; flex-flow: column; flex: 1; vertical-align:top;"><div style="width: 100%; display: block; background-color:lightgreen;"> <p style="margin: 0.1em 0.5em;"><small>L</small>-<a href="/wiki/Aspartate" class="mw-redirect" title="Aspartate">aspartate</a></p> </div><div style="margin: auto 0"><span typeof="mw:File"><a href="/wiki/File:L-Asparagins%C3%A4ure_-_L-Aspartic_acid.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/ce/L-Asparagins%C3%A4ure_-_L-Aspartic_acid.svg/75px-L-Asparagins%C3%A4ure_-_L-Aspartic_acid.svg.png" decoding="async" width="75" height="44" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/ce/L-Asparagins%C3%A4ure_-_L-Aspartic_acid.svg/113px-L-Asparagins%C3%A4ure_-_L-Aspartic_acid.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/ce/L-Asparagins%C3%A4ure_-_L-Aspartic_acid.svg/150px-L-Asparagins%C3%A4ure_-_L-Aspartic_acid.svg.png 2x" data-file-width="205" data-file-height="121" /></a></span></div> </div> <span class="nowrap">+ <a href="/wiki/Adenosine_triphosphate" title="Adenosine triphosphate">ATP</a></span> </td> <td rowspan="2" style="text-align:left;padding-left:1em"><span typeof="mw:File"><a href="/wiki/File:Biochem_reaction_arrow_forward_YNNY_vert_med.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/8/8f/Biochem_reaction_arrow_forward_YNNY_vert_med.svg/75px-Biochem_reaction_arrow_forward_YNNY_vert_med.svg.png" decoding="async" width="75" height="75" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/8f/Biochem_reaction_arrow_forward_YNNY_vert_med.svg/113px-Biochem_reaction_arrow_forward_YNNY_vert_med.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/8f/Biochem_reaction_arrow_forward_YNNY_vert_med.svg/150px-Biochem_reaction_arrow_forward_YNNY_vert_med.svg.png 2x" data-file-width="75" data-file-height="75" /></a></span> </td> <td rowspan="2"><div style="margin: 1em 1em -1em auto; width:75px"><span typeof="mw:File"><a href="/wiki/File:Biochem_reaction_arrow_reverse_NYYN_vert_med.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/6e/Biochem_reaction_arrow_reverse_NYYN_vert_med.svg/75px-Biochem_reaction_arrow_reverse_NYYN_vert_med.svg.png" decoding="async" width="75" height="75" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/6e/Biochem_reaction_arrow_reverse_NYYN_vert_med.svg/113px-Biochem_reaction_arrow_reverse_NYYN_vert_med.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/6e/Biochem_reaction_arrow_reverse_NYYN_vert_med.svg/150px-Biochem_reaction_arrow_reverse_NYYN_vert_med.svg.png 2x" data-file-width="75" data-file-height="75" /></a></span></div> </td></tr> <tr> <td style="text-align:right;">PP<sub>i</sub> + <a href="/wiki/Adenosine_monophosphate" title="Adenosine monophosphate">AMP</a> </td> <td style="text-align:left;vertical-align: top;padding-top:0.5em" rowspan="2">H<sub>2</sub>O </td></tr> <tr style="vertical-align: top"> <td rowspan="2"> </td> <td rowspan="2" style="text-align:center;"><div style="text-align: center; display: inline-block; display: inline-flex; flex-flow: column; flex: 1; vertical-align:top; margin: -15px 1em 0 -1em"><div style="margin: auto 0"><span typeof="mw:File"><a href="/wiki/File:Argininosuccinic_acid.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/28/Argininosuccinic_acid.png/140px-Argininosuccinic_acid.png" decoding="async" width="140" height="134" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/28/Argininosuccinic_acid.png/210px-Argininosuccinic_acid.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/28/Argininosuccinic_acid.png/280px-Argininosuccinic_acid.png 2x" data-file-width="575" data-file-height="550" /></a></span></div> <div style="width: 100%; display: block; background-color:lightgreen;"> <p style="margin: 0.1em 0.5em;"><small>L</small>-<a href="/wiki/Argininosuccinic_acid" title="Argininosuccinic acid">argininosuccinate</a></p> </div> </div> </td> <td style="text-align:center;"><span typeof="mw:File"><a href="/wiki/File:Biochem_reaction_arrow_forward_NNYN_horiz_med.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d2/Biochem_reaction_arrow_forward_NNYN_horiz_med.svg/75px-Biochem_reaction_arrow_forward_NNYN_horiz_med.svg.png" decoding="async" width="75" height="75" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/d2/Biochem_reaction_arrow_forward_NNYN_horiz_med.svg/113px-Biochem_reaction_arrow_forward_NNYN_horiz_med.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/d2/Biochem_reaction_arrow_forward_NNYN_horiz_med.svg/150px-Biochem_reaction_arrow_forward_NNYN_horiz_med.svg.png 2x" data-file-width="75" data-file-height="75" /></a></span> </td> <td rowspan="2"><div style="text-align: center; display: inline-block; display: inline-flex; flex-flow: column; flex: 1; vertical-align:top; margin: 1em -1em 0 1em"><div style="margin: auto 0"><span typeof="mw:File"><a href="/wiki/File:L-Arginin_-_L-Arginine.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4d/L-Arginin_-_L-Arginine.svg/140px-L-Arginin_-_L-Arginine.svg.png" decoding="async" width="140" height="51" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4d/L-Arginin_-_L-Arginine.svg/210px-L-Arginin_-_L-Arginine.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4d/L-Arginin_-_L-Arginine.svg/280px-L-Arginin_-_L-Arginine.svg.png 2x" data-file-width="335" data-file-height="121" /></a></span></div> <div style="width: 100%; display: block; background-color:lightgreen;"> <p style="margin: 0.1em 0.5em;"><small>L</small>-<a href="/wiki/Arginine" title="Arginine">arginine</a></p> </div> </div> </td></tr> <tr> <td style="text-align:center;vertical-align:bottom"><style data-mw-deduplicate="TemplateStyles:r1053752524">.mw-parser-output .template-imageflip-horiz img{transform:scaleX(-1);transform-origin:center}.mw-parser-output .template-imageflip-vert img{transform:scaleY(-1);transform-origin:center}</style><div class="template-imageflip-horiz"><div style="text-align: center; display: inline-block; display: inline-flex; flex-flow: column; flex: 1; vertical-align:top; margin-top:-15px"><div style="margin: auto 0"><span typeof="mw:File"><a href="/wiki/File:Fumars%C3%A4ure.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Fumars%C3%A4ure.svg/100px-Fumars%C3%A4ure.svg.png" decoding="async" width="100" height="53" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Fumars%C3%A4ure.svg/150px-Fumars%C3%A4ure.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Fumars%C3%A4ure.svg/200px-Fumars%C3%A4ure.svg.png 2x" data-file-width="221" data-file-height="117" /></a></span></div> <div style="width: 100%; display: block; background-color:lightgreen;"> <p style="margin: 0.1em 0.5em;"><a href="/wiki/Fumarate" class="mw-redirect" title="Fumarate">Fumarate</a></p> </div> </div></div> </td></tr></tbody></table> </td></tr> <tr> <td colspan="17" style="background: transparent; padding: 0px"> </td></tr></tbody></table> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Metabolism:_amino_acid_metabolism_-_urea_cycle_enzymes" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Urea_cycle_enzymes" title="Template:Urea cycle enzymes"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Urea_cycle_enzymes" title="Template talk:Urea cycle enzymes"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Urea_cycle_enzymes" title="Special:EditPage/Template:Urea cycle enzymes"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Metabolism:_amino_acid_metabolism_-_urea_cycle_enzymes" style="font-size:114%;margin:0 4em"><a href="/wiki/Metabolism" title="Metabolism">Metabolism</a>: <a href="/wiki/Protein_metabolism" title="Protein metabolism">amino acid metabolism</a> - <a class="mw-selflink selflink">urea cycle</a> <a href="/wiki/Enzyme" title="Enzyme">enzymes</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Main cycle</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Mitochondrial_matrix" title="Mitochondrial matrix">mitochondrial matrix</a>:</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Carbamoyl_phosphate_synthetase_I" title="Carbamoyl phosphate synthetase I">Carbamoyl phosphate synthetase I</a></li> <li><a href="/wiki/Ornithine_transcarbamylase" title="Ornithine transcarbamylase">Ornithine transcarbamylase</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Cytosol" title="Cytosol">cytosol</a>:</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Argininosuccinate_synthase" title="Argininosuccinate synthase">Argininosuccinate synthetase</a></li> <li><a href="/wiki/Argininosuccinate_lyase" title="Argininosuccinate lyase">Argininosuccinate lyase</a></li> <li><a href="/wiki/Arginase" title="Arginase">Arginase</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Regulatory/transport</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/N-Acetylglutamate_synthase" title="N-Acetylglutamate synthase">N-Acetylglutamate synthase</a></li> <li><a href="/wiki/Ornithine_translocase" title="Ornithine translocase">Ornithine translocase</a></li></ul> </div></td></tr></tbody></table></div>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" href="https://en.wikipedia.org/w/index.php?title=Urea_cycle&oldid=1236581440">https://en.wikipedia.org/w/index.php?title=Urea_cycle&oldid=1236581440</a>"</div></div> <div id="catlinks" class="catlinks" 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