CINXE.COM

<!DOCTYPE html> <html class="client-nojs" lang="en" dir="ltr"> <head> <meta charset="UTF-8"/> <title>Amino acid - Citizendium</title> <script>document.documentElement.className="client-js";RLCONF={"wgBreakFrames":false,"wgSeparatorTransformTable":["",""],"wgDigitTransformTable":["",""],"wgDefaultDateFormat":"dmy","wgMonthNames":["","January","February","March","April","May","June","July","August","September","October","November","December"],"wgRequestId":"0d6faf9086b33f222d99d0a3","wgCSPNonce":false,"wgCanonicalNamespace":"","wgCanonicalSpecialPageName":false,"wgNamespaceNumber":0,"wgPageName":"Amino_acid","wgTitle":"Amino acid","wgCurRevisionId":961898,"wgRevisionId":961898,"wgArticleId":27378,"wgIsArticle":true,"wgIsRedirect":false,"wgAction":"view","wgUserName":null,"wgUserGroups":["*"],"wgCategories":["Chemistry tag","Biology tag","Biochemistry tag","Suggestion Bot Tag","CZ Live","Chemistry Workgroup","Biology Workgroup","Biochemistry Subgroup","Articles written in British English","All Content","Chemistry Content","Biology Content"],"wgPageContentLanguage":"en","wgPageContentModel":"wikitext","wgRelevantPageName": "Amino_acid","wgRelevantArticleId":27378,"wgIsProbablyEditable":false,"wgRelevantPageIsProbablyEditable":false,"wgRestrictionEdit":[],"wgRestrictionMove":[],"wgRedirectedFrom":"Amino_acids","wgPageFormsTargetName":null,"wgPageFormsAutocompleteValues":[],"wgPageFormsAutocompleteOnAllChars":false,"wgPageFormsFieldProperties":[],"wgPageFormsCargoFields":[],"wgPageFormsDependentFields":[],"wgPageFormsCalendarValues":[],"wgPageFormsCalendarParams":[],"wgPageFormsCalendarHTML":null,"wgPageFormsGridValues":[],"wgPageFormsGridParams":[],"wgPageFormsContLangYes":null,"wgPageFormsContLangNo":null,"wgPageFormsContLangMonths":[],"wgPageFormsHeightForMinimizingInstances":800,"wgPageFormsShowOnSelect":[],"wgPageFormsScriptPath":"/wiki/extensions/PageForms","edgValues":null,"wgPageFormsEDSettings":null,"wgAmericanDates":false,"wgVector2022PreviewPages":[],"wgMediaViewerOnClick":true,"wgMediaViewerEnabledByDefault":true,"wgPopupsFlags":4,"wgInternalRedirectTargetUrl":"/wiki/Amino_acid"};RLSTATE={ "site.styles":"ready","user.styles":"ready","user":"ready","user.options":"loading","ext.math.styles":"ready","skins.vector.styles.legacy":"ready"};RLPAGEMODULES=["mediawiki.action.view.redirect","ext.math.scripts","site","mediawiki.page.ready","mediawiki.toc","skins.vector.legacy.js","mmv.head","mmv.bootstrap.autostart","ext.gadget.charinsert","ext.popups"];</script> <script>(RLQ=window.RLQ||[]).push(function(){mw.loader.implement("user.options@12s5i",function($,jQuery,require,module){mw.user.tokens.set({"patrolToken":"+\\","watchToken":"+\\","csrfToken":"+\\"});});});</script> <link rel="stylesheet" href="/wiki/load.php?lang=en&modules=ext.math.styles%7Cskins.vector.styles.legacy&only=styles&skin=vector"/> <script async="" src="/wiki/load.php?lang=en&modules=startup&only=scripts&raw=1&skin=vector"></script> <meta name="ResourceLoaderDynamicStyles" content=""/> <link rel="stylesheet" href="/wiki/load.php?lang=en&modules=site.styles&only=styles&skin=vector"/> <meta name="generator" content="MediaWiki 1.39.5"/> <meta name="format-detection" content="telephone=no"/> <meta property="og:image" content="https://citizendium.org/wiki/images/a/a5/Twenty_amino_acid_structures3.jpg"/> <meta property="og:image:width" content="1200"/> <meta property="og:image:height" content="1692"/> <meta property="og:image" content="https://citizendium.org/wiki/images/a/a5/Twenty_amino_acid_structures3.jpg"/> <meta property="og:image:width" content="800"/> <meta property="og:image:height" content="1128"/> <meta property="og:image" content="https://citizendium.org/wiki/images/thumb/a/a5/Twenty_amino_acid_structures3.jpg/640px-Twenty_amino_acid_structures3.jpg"/> <meta property="og:image:width" content="640"/> <meta property="og:image:height" content="903"/> <meta name="viewport" content="width=1000"/> <link rel="icon" href="/images/favicon1.ico"/> <link rel="search" type="application/opensearchdescription+xml" href="/wiki/opensearch_desc.php" title="Citizendium"/> <link rel="EditURI" type="application/rsd+xml" href="https://citizendium.org/wiki/api.php?action=rsd"/> <link rel="license" href="https://creativecommons.org/licenses/by-nc-sa/4.0/"/> <link rel="alternate" type="application/atom+xml" title="Citizendium Atom feed" href="/wiki/index.php?title=Special:RecentChanges&feed=atom"/> <link rel="canonical" href="https://citizendium.org/wiki/Amino_acid"/> <script async src="https://www.googletagmanager.com/gtag/js?id=G-W7ML9SNPXT"></script> <script> window.dataLayer = window.dataLayer || []; function gtag(){dataLayer.push(arguments);} gtag('js', new Date()); gtag('config', 'G-W7ML9SNPXT'); </script> </head> <body class="mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject page-Amino_acid rootpage-Amino_acid skin-vector action-view skin-vector-legacy vector-feature-language-in-header-enabled vector-feature-language-in-main-page-header-disabled vector-feature-language-alert-in-sidebar-disabled vector-feature-sticky-header-disabled vector-feature-sticky-header-edit-disabled vector-feature-table-of-contents-disabled vector-feature-visual-enhancement-next-disabled"><div id="mw-page-base" class="noprint"></div> <div id="mw-head-base" class="noprint"></div> <div id="content" class="mw-body" role="main"> <a id="top"></a> <div id="siteNotice"></div> <div class="mw-indicators"> </div> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Amino acid</span></h1> <div id="bodyContent" class="vector-body"> <div id="siteSub" class="noprint">From Citizendium</div> <div id="contentSub"><span class="mw-redirectedfrom">(Redirected from <a href="/wiki/index.php?title=Amino_acids&redirect=no" class="mw-redirect" title="Amino acids">Amino acids</a>)</span></div> <div id="contentSub2"></div> <div id="jump-to-nav"></div> <a class="mw-jump-link" href="#mw-head">Jump to navigation</a> <a class="mw-jump-link" href="#searchInput">Jump to search</a> <div id="mw-content-text" class="mw-body-content mw-content-ltr" lang="en" dir="ltr"><div class="mw-parser-output"><div style="float:right;"><div style="position:relative; top: -20px;"> <div style="cursor: pointer" onClick="return addthis_open(this, '', 'https://en.citizendium.org/wiki/Amino acid', 'Amino acid')" onmouseout="addthis_close()"><img src="//s9.addthis.com/button1-share.gif" width="125" height="16" border="0" alt="" /></div>   <script type="text/javascript"> addthis_pub = 'citizendium'; addthis_logo = ''; addthis_logo_color = ''; addthis_logo_background = ''; addthis_brand = 'Citizendium'; addthis_options = ''; addthis_offset_top = ''; addthis_offset_left = ''; </script><script type="text/javascript" src="//s7.addthis.com/js/152/addthis_widget.js"></script>  </div></div><div align="left" style="background-color: #cccccc; margin:0.5em;position:relative;"> <table class="noprint" width="100%" border="0" cellpadding="4" cellspacing="0" style="background:#f3f3f3"> <tbody><tr> <td rowspan="2" width="2px" valign="top" align="left" style="background:#C4D2DF; border-left:1px solid #aaaaaa; border-bottom:1px solid #aaaaaa; border-top:1px solid #aaaaaa; border-right:1px solid #aaaaaa;"><a href="/wiki/File:Statusbar2.png" class="image" title="This article is developing and not approved."><img alt="This article is developing and not approved." src="/wiki/images/4/4f/Statusbar2.png" decoding="async" width="12" height="59" data-file-width="12" data-file-height="59" /></a><br /> </td> <td align="center" bgcolor="#C4D2DF" style="border-bottom:1px solid #C4D2DF; white-space: nowrap; border-top:1px solid #aaaaaa; border-right:1px solid #aaaaaa; font-size:0.9em;"><font size="2"><a class="mw-selflink selflink">Main Article</a></font><br /> </td> <td align="center" bgcolor="#CCCCCC" style="white-space: nowrap; border-bottom:1px solid #aaaaaa; border-top:1px solid #aaaaaa; border-right:1px solid #aaaaaa; font-size:0.9em;"><font size="2"><a href="/wiki/Talk:Amino_acid" title="Talk:Amino acid">Discussion</a></font> <br /> </td> <td align="center" bgcolor="#CCCCCC" style="white-space: nowrap; border-bottom:1px solid #aaaaaa; border-top:1px solid #aaaaaa; border-right:1px solid #aaaaaa; font-size:0.9em;"><a href="/wiki/Amino_acid/Related_Articles" title="Amino acid/Related Articles">Related Articles </a> <a href="/wiki/CZ:Related_Articles" title="CZ:Related Articles"><span style="font-size:0.9em;"><sup>[?]</sup></span></a> <br /> </td> <td align="center" bgcolor="#CCCCCC" style="white-space: nowrap; border-bottom:1px solid #aaaaaa; border-top:1px solid #aaaaaa; border-right:1px solid #aaaaaa; font-size:0.9em;"><a href="/wiki/Amino_acid/Bibliography" title="Amino acid/Bibliography">Bibliography </a> <a href="/wiki/CZ:Bibliography" title="CZ:Bibliography"><span style="font-size:0.9em;"><sup>[?]</sup></span></a> <br /> </td> <td align="center" bgcolor="#CCCCCC" style="white-space: nowrap; border-bottom:1px solid #aaaaaa; border-top:1px solid #aaaaaa; border-right:1px solid #aaaaaa; font-size:0.9em;"><a rel="nofollow" class="external text" href="http://en.citizendium.org/wiki/index.php?action=edit&preload=Template%3ASubpages_name&title=Amino_acid/External_Links"><font color="#810541">External Links </font></a> <a href="/wiki/CZ:External_Links" title="CZ:External Links"><span style="font-size:0.9em;"><sup>[?]</sup></span></a> <br /> </td> <td align="center" bgcolor="#CCCCCC" style="white-space: nowrap; border-bottom:1px solid #aaaaaa; border-top:1px solid #aaaaaa; border-right:1px solid #aaaaaa; font-size:0.9em;"><a rel="nofollow" class="external text" href="http://en.citizendium.org/wiki?action=edit&preload=Template%3ACitable_Version_start&title=Amino_acid/Citable_Version"><font color="#810541">Citable Version </font></a> <a href="/wiki/CZ:Citable_Version" title="CZ:Citable Version"><span style="font-size:0.9em;"><sup>[?]</sup></span></a> <br /> </td> <td align="center" bgcolor="#CCCCCC" style="white-space: nowrap; border-bottom:1px solid #aaaaaa; border-top:1px solid #aaaaaa; border-right:1px solid #aaaaaa; font-size:0.9em;"><div style="position:relative; width:14px; height:14px; overflow:hidden;"><div style="position:absolute; font-size:14px; overflow:hidden; line-height:14px; letter-spacing:14px;"><a href="/wiki/CZ:Subpages" title="CZ:Subpages"><span title="CZ:Subpages" style="text-decoration:none;">   </span></a></div><a href="/wiki/File:Subpages.png" class="image" title="CZ:Subpages"><img alt="CZ:Subpages" src="/wiki/images/thumb/1/1f/Subpages.png/14px-Subpages.png" decoding="async" width="14" height="14" srcset="/wiki/images/1/1f/Subpages.png 1.5x" data-file-width="17" data-file-height="17" /></a></div><div style="position:relative; width:14px; height:14px; overflow:hidden;"><div style="position:absolute; font-size:14px; overflow:hidden; line-height:14px; letter-spacing:14px;"><a href="/wiki/Template:Amino_acid/Metadata" title="Template:Amino acid/Metadata"><span title="Template:Amino acid/Metadata" style="text-decoration:none;">   </span></a></div><a href="/wiki/File:Metadata.png" class="image" title="Template:Amino acid/Metadata"><img alt="Template:Amino acid/Metadata" src="/wiki/images/thumb/4/4f/Metadata.png/14px-Metadata.png" decoding="async" width="14" height="14" srcset="/wiki/images/4/4f/Metadata.png 1.5x" data-file-width="17" data-file-height="17" /></a></div> </td> <td width="100%" style="background-color: #f3f3f3; border-bottom:1px solid #aaaaaa">  </td></tr> <tr> <td height="40px" colspan="20" style="background:#C4D2DF; padding: 2px 2px 2px 2px; border-right:1px solid #aaaaaa; border-bottom:1px solid #aaaaaa"> <table align="right" border="0" cellpadding="2" cellspacing="0"> <tbody><tr> <td><div class="plainlinks plainlinksneverexpand" style="position:relative; width:17px; height:17px; overflow:hidden; text-decoration:none;"><div style="position:absolute; font-size:17px; overflow:hidden; line-height:17px; letter-spacing:17px;"><a rel="nofollow" class="external text" href="https://en.citizendium.org/wiki/index.php?title=Amino_acid&printable=yes"><span title="https://en.citizendium.org/wiki/index.php?title=Amino_acid&printable=yes" style="text-decoration:none;">   </span></a></div><a href="/wiki/File:Print_button.png" class="image" title="https://en.citizendium.org/wiki/index.php?title=Amino_acid&printable=yes"><img alt="https://en.citizendium.org/wiki/index.php?title=Amino_acid&printable=yes" src="/wiki/images/thumb/0/07/Print_button.png/17px-Print_button.png" decoding="async" width="17" height="17" srcset="/wiki/images/thumb/0/07/Print_button.png/26px-Print_button.png 1.5x, /wiki/images/thumb/0/07/Print_button.png/34px-Print_button.png 2x" data-file-width="45" data-file-height="45" /></a></div> </td></tr></tbody></table><font size="2"><i>This editable Main Article is <b>under development</b> and subject to a <a href="/wiki/CZ:Disclaimer" title="CZ:Disclaimer"><b>disclaimer</b></a><b>. </b></i><b></b></font><div style="float:right; margin: .1em .5em;"><b>[<span class="plainlinks plainlinksneverexpand"><a rel="nofollow" class="external text" href="https://citizendium.org/wiki/index.php?title=Amino_acid&action=edit&section=0"><font size="2">edit intro</font></a></span>]</b></div> </td></tr></tbody></table></div> <div class="thumb tright"><div class="thumbinner" style="width:502px;"><a href="/wiki/File:Twenty_amino_acid_structures3.jpg" class="image"><img alt="" src="/wiki/images/thumb/a/a5/Twenty_amino_acid_structures3.jpg/500px-Twenty_amino_acid_structures3.jpg" decoding="async" width="500" height="705" class="thumbimage" srcset="/wiki/images/thumb/a/a5/Twenty_amino_acid_structures3.jpg/750px-Twenty_amino_acid_structures3.jpg 1.5x, /wiki/images/a/a5/Twenty_amino_acid_structures3.jpg 2x" data-file-width="780" data-file-height="1100" /></a> <div class="thumbcaption"><div class="magnify"><a href="/wiki/File:Twenty_amino_acid_structures3.jpg" class="internal" title="Enlarge"></a></div><span style="font-size:0.8em; color:rgb(125, 125, 125);">(CC) Image: David E. Volk</span> <br />Amino acid structures.</div></div></div> <p>In <a href="/wiki/Biochemistry" title="Biochemistry">biochemistry</a>, an <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \alpha }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>α</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \alpha }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/b79333175c8b3f0840bfb4ec41b8072c83ea88d3" class="mwe-math-fallback-image-inline" aria-hidden="true" style="vertical-align: -0.338ex; width:1.488ex; height:1.676ex;" alt="{\displaystyle \alpha }"/></span>-<b>amino acid</b> is an <a href="/wiki/Organic_chemistry" title="Organic chemistry">organic</a> <a href="/wiki/Monomer" title="Monomer">monomer</a> consisting of an <a href="/wiki/index.php?title=Amino_group&action=edit&redlink=1" class="new" title="Amino group (page does not exist)">amino group</a>, a <a href="/wiki/index.php?title=Carboxyl_group&action=edit&redlink=1" class="new" title="Carboxyl group (page does not exist)">carboxyl group</a>, a <a href="/wiki/Hydrogen" title="Hydrogen">hydrogen</a> atom, and a residual group (commonly denoted as simply "R") <a href="/wiki/index.php?title=Covalent_bond&action=edit&redlink=1" class="new" title="Covalent bond (page does not exist)">covalently</a> bonded to a central (alpha) carbon (C<sub><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \alpha }"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>α</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \alpha }</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/b79333175c8b3f0840bfb4ec41b8072c83ea88d3" class="mwe-math-fallback-image-inline" aria-hidden="true" style="vertical-align: -0.338ex; width:1.488ex; height:1.676ex;" alt="{\displaystyle \alpha }"/></span></sub>). Amino acids can link via <a href="/wiki/index.php?title=Peptide_bond&action=edit&redlink=1" class="new" title="Peptide bond (page does not exist)">peptide bonds</a> to create short chains (polymers) called <a href="/wiki/Polypeptide" title="Polypeptide">polypeptides</a>, often referred to simply as peptides. Longer, more complex chains (or combinations of multiple chains) are called <a href="/wiki/Protein" title="Protein">proteins</a>, which have a vast array of biological functions. In peptides and proteins, the R-groups are often called "side chains", because they are not involved in the polymer backbone. Amino acids have two stereo isomers (mirror images of each other), and only the L-isomer is used in protein synthesis. </p> <div id="toc" class="toc" role="navigation" aria-labelledby="mw-toc-heading"><input type="checkbox" role="button" id="toctogglecheckbox" class="toctogglecheckbox" style="display:none" /><div class="toctitle" lang="en" dir="ltr"><h2 id="mw-toc-heading">Contents</h2><span class="toctogglespan"><label class="toctogglelabel" for="toctogglecheckbox"></label></span></div> <ul> <li class="toclevel-1 tocsection-1"><a href="#The_Amino_Acids"><span class="tocnumber">1</span> <span class="toctext">The Amino Acids</span></a> <ul> <li class="toclevel-2 tocsection-2"><a href="#Amino_Acids_with_Non-Polar_R-Groups"><span class="tocnumber">1.1</span> <span class="toctext">Amino Acids with Non-Polar R-Groups</span></a></li> <li class="toclevel-2 tocsection-3"><a href="#Amino_Acids_with_Aromatic_R-Groups"><span class="tocnumber">1.2</span> <span class="toctext">Amino Acids with Aromatic R-Groups</span></a></li> <li class="toclevel-2 tocsection-4"><a href="#Amino_Acids_with_Polar,_Uncharged_R-Groups"><span class="tocnumber">1.3</span> <span class="toctext">Amino Acids with Polar, Uncharged R-Groups</span></a></li> <li class="toclevel-2 tocsection-5"><a href="#Amino_Acids_with_Positively_Charged_R-Groups"><span class="tocnumber">1.4</span> <span class="toctext">Amino Acids with Positively Charged R-Groups</span></a></li> <li class="toclevel-2 tocsection-6"><a href="#Amino_Acids_with_Negatively_Charged_R-Groups"><span class="tocnumber">1.5</span> <span class="toctext">Amino Acids with Negatively Charged R-Groups</span></a></li> </ul> </li> <li class="toclevel-1 tocsection-7"><a href="#Synthesis"><span class="tocnumber">2</span> <span class="toctext">Synthesis</span></a></li> <li class="toclevel-1 tocsection-8"><a href="#See_Also"><span class="tocnumber">3</span> <span class="toctext">See Also</span></a></li> </ul> </div> <h2><span class="mw-headline" id="The_Amino_Acids">The Amino Acids</span></h2> <p>There are twenty common amino acids used by nearly all living <a href="/wiki/Organism" title="Organism">organisms</a> as well as several rarer ones. The difference between any two amino acids is the residual (R) group, and they can be categorized based on the <a href="/wiki/index.php?title=Chemical_property&action=edit&redlink=1" class="new" title="Chemical property (page does not exist)">chemical properties</a> of the R-groups. Each amino acid has a three-letter abbreviation and a one-letter symbol. </p> <h4><span class="mw-headline" id="Amino_Acids_with_Non-Polar_R-Groups">Amino Acids with <a href="/wiki/index.php?title=Polar&action=edit&redlink=1" class="new" title="Polar (page does not exist)">Non-Polar</a> R-Groups</span></h4> <dl><dd><ul><li><a href="/wiki/Glycine" title="Glycine">Glycine</a> (Gly, G)</li> <li><a href="/wiki/Alanine" title="Alanine">Alanine</a> (Ala, A)</li> <li><a href="/wiki/Valine" title="Valine">Valine</a> (Val, V)</li> <li><a href="/wiki/Leucine" title="Leucine">Leucine</a> (Leu, L)</li> <li><a href="/wiki/Isoleucine" title="Isoleucine">Isoleucine</a> (Ile, I)</li> <li><a href="/wiki/Methionine" title="Methionine">Methionine</a> (Met, M), which may be demethylated to <a href="/wiki/Homocysteine" title="Homocysteine">homocysteine</a>.</li></ul></dd></dl> <h4><span class="mw-headline" id="Amino_Acids_with_Aromatic_R-Groups">Amino Acids with <a href="/wiki/Aromatic" class="mw-redirect" title="Aromatic">Aromatic</a> R-Groups</span></h4> <dl><dd><ul><li><a href="/wiki/Phenylalanine" title="Phenylalanine">Phenylalanine</a> (Phe, F)</li> <li><a href="/wiki/Tyrosine" title="Tyrosine">Tyrosine</a> (Tyr, Y)</li> <li><a href="/wiki/Tryptophan" title="Tryptophan">Tryptophan</a> (Trp, W)</li></ul></dd></dl> <h4><span id="Amino_Acids_with_Polar.2C_Uncharged_R-Groups"></span><span class="mw-headline" id="Amino_Acids_with_Polar,_Uncharged_R-Groups">Amino Acids with <a href="/wiki/index.php?title=Polar&action=edit&redlink=1" class="new" title="Polar (page does not exist)">Polar</a>, <a href="/wiki/Electric_charge" title="Electric charge">Uncharged</a> R-Groups</span></h4> <dl><dd><ul><li><a href="/wiki/Serine" title="Serine">Serine</a> (Ser, S)</li> <li><a href="/wiki/Threonine" title="Threonine">Threonine</a> (Thr, T)</li> <li><a href="/wiki/Cysteine" title="Cysteine">Cysteine</a> (Cys, C)</li> <li><a href="/wiki/Proline" title="Proline">Proline</a> (Pro, P)</li> <li><a href="/wiki/Asparagine" title="Asparagine">Asparagine</a> (Asn, N)</li> <li><a href="/wiki/Glutamine" title="Glutamine">Glutamine</a> (Gln, Q)</li></ul></dd></dl> <h4><span class="mw-headline" id="Amino_Acids_with_Positively_Charged_R-Groups">Amino Acids with <a href="/wiki/Electric_charge" title="Electric charge">Positively Charged</a> R-Groups</span></h4> <dl><dd><ul><li><a href="/wiki/Lysine" title="Lysine">Lysine</a> (Lys, K)</li> <li><a href="/wiki/Arginine" title="Arginine">Arginine</a> (Arg, R)</li> <li><a href="/wiki/Histidine" title="Histidine">Histidine</a> (His, H)</li></ul></dd></dl> <h4><span class="mw-headline" id="Amino_Acids_with_Negatively_Charged_R-Groups">Amino Acids with <a href="/wiki/Electric_charge" title="Electric charge">Negatively Charged</a> R-Groups</span></h4> <dl><dd><ul><li><a href="/wiki/Aspartic_acid" title="Aspartic acid">Aspartic acid</a>, or aspartate (Asp, D)</li> <li><a href="/wiki/Glutamic_acid" title="Glutamic acid">Glutamic acid</a> or glutamate (Glu, E)</li></ul></dd></dl> <h2><span class="mw-headline" id="Synthesis">Synthesis</span></h2> <p>Most organisms are unable to <a href="/wiki/index.php?title=Synthesis&action=edit&redlink=1" class="new" title="Synthesis (page does not exist)">synthesize</a> all twenty amino acids. <i>Essential</i> amino acids must be taken in from the environment, whereas <i>nonessential</i> amino acids can be produced by the organism. For humans, there are seven essential amino acids that must be obtained in the <a href="/wiki/Diet" class="mw-redirect" title="Diet">diet</a> in order to survive; there are therefore thirteen non-essential amino acids for humans. The number of and the identity of the essential amino acids varies among <a href="/wiki/Species" class="mw-redirect" title="Species">species</a>. </p><p>For humans, the nonessential amino acids can be synthesized in <a href="/wiki/Cell_(biology)" title="Cell (biology)">cells</a> through a variety of pathways. For some animals, the amino acid <a href="/wiki/Carnitine" title="Carnitine">carnitine</a> is essential, but most animals can produce it from lysine. </p> <h2><span class="mw-headline" id="See_Also">See Also</span></h2> <ul><li><a href="/wiki/Protein" title="Protein">Protein</a></li> <li><a href="/wiki/Biochemistry" title="Biochemistry">Biochemistry</a></li> <li><a href="/wiki/index.php?title=Transfer_RNA&action=edit&redlink=1" class="new" title="Transfer RNA (page does not exist)">Transfer RNA</a></li></ul>  </div> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" href="https://citizendium.org/wiki/index.php?title=Amino_acid&oldid=961898">https://citizendium.org/wiki/index.php?title=Amino_acid&oldid=961898</a>"</div></div> <div id="catlinks" class="catlinks" data-mw="interface"><div id="mw-normal-catlinks" class="mw-normal-catlinks"><a href="/wiki/Special:Categories" title="Special:Categories">Categories</a>: <ul><li><a href="/wiki/Category:CZ_Live" title="Category:CZ Live">CZ Live</a></li><li><a href="/wiki/Category:Chemistry_Workgroup" title="Category:Chemistry Workgroup">Chemistry Workgroup</a></li><li><a href="/wiki/Category:Biology_Workgroup" title="Category:Biology Workgroup">Biology Workgroup</a></li><li><a href="/wiki/Category:Biochemistry_Subgroup" title="Category:Biochemistry Subgroup">Biochemistry Subgroup</a></li><li><a href="/wiki/Category:Articles_written_in_British_English" title="Category:Articles written in British English">Articles written in British English</a></li><li><a href="/wiki/Category:All_Content" title="Category:All Content">All Content</a></li><li><a href="/wiki/Category:Chemistry_Content" title="Category:Chemistry Content">Chemistry Content</a></li><li><a href="/wiki/Category:Biology_Content" title="Category:Biology Content">Biology Content</a></li></ul></div><div id="mw-hidden-catlinks" class="mw-hidden-catlinks mw-hidden-cats-hidden">Hidden categories: <ul><li><a href="/wiki/Category:Chemistry_tag" title="Category:Chemistry tag">Chemistry tag</a></li><li><a href="/wiki/Category:Biology_tag" title="Category:Biology tag">Biology tag</a></li><li><a href="/wiki/Category:Biochemistry_tag" title="Category:Biochemistry tag">Biochemistry tag</a></li><li><a href="/wiki/Category:Suggestion_Bot_Tag" title="Category:Suggestion Bot Tag">Suggestion Bot Tag</a></li></ul></div></div> </div> </div> <div id="mw-navigation"> <h2>Navigation menu</h2> <div id="mw-head"> <nav id="p-personal" class="vector-menu mw-portlet mw-portlet-personal vector-user-menu-legacy" aria-labelledby="p-personal-label" role="navigation" > <h3 id="p-personal-label" class="vector-menu-heading " > <span class="vector-menu-heading-label">Personal tools</span> </h3> <div class="vector-menu-content"> <ul class="vector-menu-content-list"><li id="pt-login" class="mw-list-item"><a href="/wiki/index.php?title=Special:UserLogin&returnto=Amino+acid" title="To edit pages, [[Special:RequestAccount|get a contributor account]]. [o]" accesskey="o"><span>Log in</span></a></li></ul> </div> </nav> <div id="left-navigation"> <nav id="p-namespaces" class="vector-menu mw-portlet mw-portlet-namespaces vector-menu-tabs vector-menu-tabs-legacy" aria-labelledby="p-namespaces-label" role="navigation" > <h3 id="p-namespaces-label" class="vector-menu-heading " > <span class="vector-menu-heading-label">Namespaces</span> </h3> <div class="vector-menu-content"> <ul class="vector-menu-content-list"><li id="ca-nstab-main" class="selected mw-list-item"><a href="/wiki/Amino_acid" title="View the content page [c]" accesskey="c"><span>Page</span></a></li><li id="ca-talk" class="mw-list-item"><a href="/wiki/Talk:Amino_acid" rel="discussion" title="Discussion about the content page [t]" accesskey="t"><span>Discussion</span></a></li></ul> </div> </nav> <nav id="p-variants" class="vector-menu mw-portlet mw-portlet-variants emptyPortlet vector-menu-dropdown" aria-labelledby="p-variants-label" role="navigation" > <input type="checkbox" id="p-variants-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-variants" class="vector-menu-checkbox" aria-labelledby="p-variants-label" /> <label id="p-variants-label" aria-label="Change language variant" class="vector-menu-heading " > <span class="vector-menu-heading-label">English</span> </label> <div class="vector-menu-content"> <ul class="vector-menu-content-list"></ul> </div> </nav> </div> <div id="right-navigation"> <nav id="p-views" class="vector-menu mw-portlet mw-portlet-views vector-menu-tabs vector-menu-tabs-legacy" aria-labelledby="p-views-label" role="navigation" > <h3 id="p-views-label" class="vector-menu-heading " > <span class="vector-menu-heading-label">Views</span> </h3> <div class="vector-menu-content"> <ul class="vector-menu-content-list"><li id="ca-view" class="selected mw-list-item"><a href="/wiki/Amino_acid"><span>Read</span></a></li><li id="ca-viewsource" class="mw-list-item"><a href="/wiki/index.php?title=Amino_acid&action=edit" title="This page is protected.
You can view its source [e]" accesskey="e"><span>View source</span></a></li><li id="ca-history" class="mw-list-item"><a href="/wiki/index.php?title=Amino_acid&action=history" title="Past revisions of this page [h]" accesskey="h"><span>View history</span></a></li><li id="ca-mzwi" class="mw-list-item"><a href="/wiki/index.php?title=Amino_acid&action=mzwi"><span>ZWI Export</span></a></li></ul> </div> </nav> <nav id="p-cactions" class="vector-menu mw-portlet mw-portlet-cactions emptyPortlet vector-menu-dropdown" aria-labelledby="p-cactions-label" role="navigation" title="More options" > <input type="checkbox" id="p-cactions-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-cactions" class="vector-menu-checkbox" aria-labelledby="p-cactions-label" /> <label id="p-cactions-label" class="vector-menu-heading " > <span class="vector-menu-heading-label">More</span> </label> <div class="vector-menu-content"> <ul class="vector-menu-content-list"></ul> </div> </nav> <div id="p-search" role="search" class="vector-search-box-vue vector-search-box-show-thumbnail vector-search-box-auto-expand-width vector-search-box"> <div> <h3 > <label for="searchInput">Search</label> </h3> <form action="/wiki/index.php" id="searchform" class="vector-search-box-form"> <div id="simpleSearch" class="vector-search-box-inner" data-search-loc="header-navigation"> <input class="vector-search-box-input" type="search" name="search" placeholder="Search Citizendium" aria-label="Search Citizendium" autocapitalize="sentences" title="Search Citizendium [f]" accesskey="f" id="searchInput" > <input type="hidden" name="title" value="Special:Search"> <input id="mw-searchButton" class="searchButton mw-fallbackSearchButton" type="submit" name="fulltext" title="Search the pages for this text" value="Search"> <input id="searchButton" class="searchButton" type="submit" name="go" title="Go to a page with this exact name if it exists" value="Go To Page"> </div> </form> </div> </div> </div> </div> <div id="mw-panel"> <div id="p-logo" role="banner"> <a class="mw-wiki-logo" href="/wiki/Welcome_to_Citizendium" title="Visit the main page"></a> </div> <nav id="p-Read" class="vector-menu mw-portlet mw-portlet-Read vector-menu-portal portal" aria-labelledby="p-Read-label" role="navigation" > <h3 id="p-Read-label" class="vector-menu-heading " > <span class="vector-menu-heading-label">Read</span> </h3> <div class="vector-menu-content"> <ul class="vector-menu-content-list"><li id="n-mainpage" class="mw-list-item"><a href="/wiki/Welcome_to_Citizendium" title="Visit the main page [z]" accesskey="z"><span>Welcome to Citizendium</span></a></li><li id="n-Citable-Articles" class="mw-list-item"><a href="/wiki/Category:Citable_versions_of_articles"><span>Citable Articles</span></a></li><li id="n-All-Articles" class="mw-list-item"><a href="/wiki/Category:CZ_Live"><span>All Articles</span></a></li><li id="n-Random-Article" class="mw-list-item"><a href="/wiki/Special:RandomInCategory/CZ_Live"><span>Random Article</span></a></li><li id="n-All-Recent-Changes" class="mw-list-item"><a href="/wiki/Special:RecentChanges"><span>All Recent Changes</span></a></li></ul> </div> </nav> <nav id="p-About_Us" class="vector-menu mw-portlet mw-portlet-About_Us vector-menu-portal portal" aria-labelledby="p-About_Us-label" role="navigation" > <h3 id="p-About_Us-label" class="vector-menu-heading " > <span class="vector-menu-heading-label">About Us</span> </h3> <div class="vector-menu-content"> <ul class="vector-menu-content-list"><li id="n-Introduction" class="mw-list-item"><a href="/wiki/CZ:About"><span>Introduction</span></a></li><li id="n-FAQ" class="mw-list-item"><a href="/wiki/CZ:FAQ"><span>FAQ</span></a></li><li id="n-Policies" class="mw-list-item"><a href="/wiki/CZ:Policies"><span>Policies</span></a></li><li id="n-Governance" class="mw-list-item"><a href="/wiki/CZ:Governance"><span>Governance</span></a></li></ul> </div> </nav> <nav id="p-Contact_Us" class="vector-menu mw-portlet mw-portlet-Contact_Us vector-menu-portal portal" aria-labelledby="p-Contact_Us-label" role="navigation" > <h3 id="p-Contact_Us-label" class="vector-menu-heading " > <span class="vector-menu-heading-label">Contact Us</span> </h3> <div class="vector-menu-content"> <ul class="vector-menu-content-list"><li id="n-Enquiries" class="mw-list-item"><a href="/wiki/CZ:Enquiry_Form"><span>Enquiries</span></a></li><li id="n-Apply-to-Join" class="mw-list-item"><a href="/wiki/Help:Index/Join"><span>Apply to Join</span></a></li><li id="n-Personnel" class="mw-list-item"><a href="/wiki/CZ:Personnel"><span>Personnel</span></a></li></ul> </div> </nav> <nav id="p-How_To" class="vector-menu mw-portlet mw-portlet-How_To vector-menu-portal portal" aria-labelledby="p-How_To-label" role="navigation" > <h3 id="p-How_To-label" class="vector-menu-heading " > <span class="vector-menu-heading-label">How To</span> </h3> <div class="vector-menu-content"> <ul class="vector-menu-content-list"><li id="n-Forum" class="mw-list-item"><a href="/wiki/Forum:Home"><span>Forum</span></a></li><li id="n-Start-Article" class="mw-list-item"><a href="/wiki/CZ:Start_Article"><span>Start Article</span></a></li><li id="n-Article-Mechanics" class="mw-list-item"><a href="/wiki/CZ:Article_mechanics"><span>Article Mechanics</span></a></li><li id="n-How-to-Edit" class="mw-list-item"><a href="/wiki/CZ:How_to_edit_an_article"><span>How to Edit</span></a></li><li id="n-Help" class="mw-list-item"><a href="/wiki/CZ:Home"><span>Help</span></a></li><li id="n-More-Help" class="mw-list-item"><a href="/wiki/Help:Index"><span>More Help</span></a></li><li id="n-Quick-Start" class="mw-list-item"><a href="/wiki/CZ:Quick_Start"><span>Quick Start</span></a></li><li id="n-How-to-collaborate" class="mw-list-item"><a href="/wiki/CZ:How_to_collaborate"><span>How to collaborate</span></a></li><li id="n-How-to-format-pages" class="mw-list-item"><a href="/wiki/CZ:How_To"><span>How to format pages</span></a></li></ul> </div> </nav> <nav id="p-Finance" class="vector-menu mw-portlet mw-portlet-Finance vector-menu-portal portal" aria-labelledby="p-Finance-label" role="navigation" > <h3 id="p-Finance-label" class="vector-menu-heading " > <span class="vector-menu-heading-label">Finance</span> </h3> <div class="vector-menu-content"> <ul class="vector-menu-content-list"><li id="n-Financial-Report" class="mw-list-item"><a href="/wiki/CZ:Financial_report"><span>Financial Report</span></a></li><li id="n-Donate" class="mw-list-item"><a href="/wiki/CZ:Donate"><span>Donate</span></a></li></ul> </div> </nav> <nav id="p-tb" class="vector-menu mw-portlet mw-portlet-tb vector-menu-portal portal" aria-labelledby="p-tb-label" role="navigation" > <h3 id="p-tb-label" class="vector-menu-heading " > <span class="vector-menu-heading-label">Tools</span> </h3> <div class="vector-menu-content"> <ul class="vector-menu-content-list"><li id="t-whatlinkshere" class="mw-list-item"><a href="/wiki/Special:WhatLinksHere/Amino_acid" title="A list of all wiki pages that link here [j]" accesskey="j"><span>What links here</span></a></li><li id="t-recentchangeslinked" class="mw-list-item"><a href="/wiki/Special:RecentChangesLinked/Amino_acid" rel="nofollow" title="Recent changes in pages linked from this page [k]" accesskey="k"><span>Related changes</span></a></li><li id="t-specialpages" class="mw-list-item"><a href="/wiki/Special:SpecialPages" title="A list of all special pages [q]" accesskey="q"><span>Special pages</span></a></li><li id="t-print" class="mw-list-item"><a href="javascript:print();" rel="alternate" title="Printable version of this page [p]" accesskey="p"><span>Printable version</span></a></li><li id="t-permalink" class="mw-list-item"><a href="/wiki/index.php?title=Amino_acid&oldid=961898" title="Permanent link to this revision of this page"><span>Permanent link</span></a></li><li id="t-info" class="mw-list-item"><a href="/wiki/index.php?title=Amino_acid&action=info" title="More information about this page"><span>Page information</span></a></li><li id="t-cite" class="mw-list-item"><a href="/wiki/index.php?title=Special:CiteThisPage&page=Amino_acid&id=961898&wpFormIdentifier=titleform" title="Information on how to cite this page"><span>Cite this page</span></a></li></ul> </div> </nav> </div> </div> <footer id="footer" class="mw-footer" role="contentinfo" > <ul id="footer-info"> <li id="footer-info-lastmod"> This page was last modified 16:00, 9 July 2024.</li> <li id="footer-info-copyright"><I>CZ is free</i>. All written content is available under the <a href="https://citizendium.org/wiki/Creative_Commons_CC-by-sa_3.0">Creative Commons-Attribution-ShareAlike 3.0 Unported license</a> or any later. Written content that originated in part from Wikipedia is also available under <a class="external" rel="nofollow" href="https://creativecommons.org/licenses/by-nc-sa/4.0/">Creative Commons Attribution-NonCommercial-ShareAlike</a>. <br /> <br /> <a href="https://citizendium.org/wiki/Help:Index">Help</a> • <a href="https://citizendium.org/wiki/CZ:Financial_report">Financial Report</a> • Follow Citizendium on <a href="https://twitter.com/TheCitizendium">Twitter</a> • <a href="https://www.facebook.com/citizendium">Facebook</a></li> </ul> <ul id="footer-places"> <li id="footer-places-privacy"><a href="/wiki/CZ:Privacy_policy">Privacy policy</a></li> <li id="footer-places-about"><a href="/wiki/CZ:About">About Citizendium</a></li> <li id="footer-places-disclaimer"><a href="/wiki/CZ:General_disclaimer">Disclaimers</a></li> </ul> <ul id="footer-icons" class="noprint"> <li id="footer-copyrightico"><a href="https://creativecommons.org/licenses/by-nc-sa/4.0/"><img src="/wiki/resources/assets/licenses/cc-by-nc-sa.png" alt="Creative Commons Attribution-NonCommercial-ShareAlike" width="88" height="31" loading="lazy"/></a></li> <li id="footer-poweredbyico"><a href="https://www.mediawiki.org/"><img src="/wiki/resources/assets/poweredby_mediawiki_88x31.png" alt="Powered by MediaWiki" srcset="/wiki/resources/assets/poweredby_mediawiki_132x47.png 1.5x, /wiki/resources/assets/poweredby_mediawiki_176x62.png 2x" width="88" height="31" loading="lazy"/></a></li> </ul> </footer> <script>(RLQ=window.RLQ||[]).push(function(){mw.config.set({"wgBackendResponseTime":830});});</script> </body> </html>