{"id":203320,"date":"2025-03-19T05:24:03","date_gmt":"2025-03-19T05:24:03","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=203320"},"modified":"2025-03-19T05:24:06","modified_gmt":"2025-03-19T05:24:06","slug":"at-ph-9-0-what-is-the-major-form-of-each-ionizable-group","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/03\/19\/at-ph-9-0-what-is-the-major-form-of-each-ionizable-group\/","title":{"rendered":"At pH 9.0, what is the major form of each ionizable group"},"content":{"rendered":"\n<p>At pH 9.0, what is the major form of each ionizable group?<br>N-terminus: ammonium; lysine R group: ammonium; C-terminus: carboxylate; aspartic acid R group: carboxylate<br>N-terminus: amine; lysine R group: ammonium; C-terminus: carboxylic acid; aspartic acid R group: carboxylic acid<br>N-terminus: amine; lysine R group: ammonium: C-terminus: carboxylic acid; aspartic acid R group: carboxylate<br>N-terminus: amine; lysine R group: ammonium: C-terminus: carboxylate; aspartic acid R group: carboxylate<\/p>\n\n\n\n<p><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-ast-global-color-6-color\"><strong>The correct answer and explanation is :<\/strong><\/mark><\/p>\n\n\n\n<p>The correct answer is:<br><strong>N-terminus: amine; lysine R group: ammonium; C-terminus: carboxylate; aspartic acid R group: carboxylate.<\/strong><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Explanation:<\/h3>\n\n\n\n<p>At <strong>pH 9.0<\/strong>, the protonation state of ionizable groups depends on their respective <strong>pKa values<\/strong>:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>N-terminal amine (pKa \u2248 9.0-10.0)<\/strong><\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The pKa of the N-terminal amine is around <strong>9.0-10.0<\/strong>.<\/li>\n\n\n\n<li>At pH <strong>9.0<\/strong>, this value is close to its pKa, meaning it will be in equilibrium between protonated (( \\text{-NH}_3^+ )) and deprotonated (( \\text{-NH}_2 )) forms.<\/li>\n\n\n\n<li>Since deprotonation starts occurring at this pH, the dominant form is <strong>neutral amine (-NH\u2082)<\/strong>.<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Lysine R-group (pKa \u2248 10.5)<\/strong><\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The lysine side chain has a pKa of around <strong>10.5<\/strong>.<\/li>\n\n\n\n<li>Since pH 9.0 is <strong>below<\/strong> its pKa, the group remains in its <strong>protonated (+1 charge) ammonium (-NH\u2083\u207a) form<\/strong>.<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>C-terminal carboxyl group (pKa \u2248 2-3)<\/strong><\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The carboxyl group has a much lower pKa (around <strong>2-3<\/strong>).<\/li>\n\n\n\n<li>Since pH 9.0 is much <strong>higher<\/strong> than its pKa, the carboxyl group will be <strong>deprotonated (-COO\u207b)<\/strong>.<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Aspartic acid R-group (pKa \u2248 3.9-4.1)<\/strong><\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The aspartic acid side chain has a pKa of around <strong>3.9-4.1<\/strong>.<\/li>\n\n\n\n<li>Since pH 9.0 is much <strong>higher<\/strong> than its pKa, the group is <strong>deprotonated (-COO\u207b)<\/strong>.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Summary of Major Forms at pH 9.0:<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>N-terminus:<\/strong> Neutral <strong>amine (-NH\u2082)<\/strong><\/li>\n\n\n\n<li><strong>Lysine R-group:<\/strong> Protonated <strong>ammonium (-NH\u2083\u207a)<\/strong><\/li>\n\n\n\n<li><strong>C-terminus:<\/strong> Deprotonated <strong>carboxylate (-COO\u207b)<\/strong><\/li>\n\n\n\n<li><strong>Aspartic acid R-group:<\/strong> Deprotonated <strong>carboxylate (-COO\u207b)<\/strong><\/li>\n<\/ul>\n\n\n\n<p>Thus, the correct answer is:<br><strong>N-terminus: amine; lysine R group: ammonium; C-terminus: carboxylate; aspartic acid R group: carboxylate.<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"<p>At pH 9.0, what is the major form of each ionizable group?N-terminus: ammonium; lysine R group: ammonium; C-terminus: carboxylate; aspartic acid R group: carboxylateN-terminus: amine; lysine R group: ammonium; C-terminus: carboxylic acid; aspartic acid R group: carboxylic acidN-terminus: amine; lysine R group: ammonium: C-terminus: carboxylic acid; aspartic acid R group: carboxylateN-terminus: amine; lysine R group: [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-203320","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/203320","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=203320"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/203320\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=203320"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=203320"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=203320"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}