{"id":640,"date":"2026-04-15T13:27:02","date_gmt":"2026-04-15T13:27:02","guid":{"rendered":"https:\/\/citations.tools.bio-logic.fr\/?p=640"},"modified":"2026-04-15T13:27:02","modified_gmt":"2026-04-15T13:27:02","slug":"use-of-235-f3y-%ce%b22-and-3-nh2y-%ce%b12-to-study-proton-coupled-electron-transfer-in-escherichia-coli-ribonucleotide-reductase","status":"publish","type":"post","link":"https:\/\/citations.tools.bio-logic.fr\/?p=640","title":{"rendered":"Use of 2,3,5-F<sub>3<\/sub>Y-\u03b22 and 3-NH<sub>2<\/sub>Y-\u03b12 To Study Proton-Coupled Electron Transfer in <i>Escherichia coli<\/i> Ribonucleotide Reductase"},"content":{"rendered":"<h4>DOI:<\/h4>\n<p><a href=\"https:\/\/doi.org\/10.1021\/bi101319v\" target=\"_blank\" rel=\"noopener\">10.1021\/bi101319v<\/a><\/p>\n<h4>Authors:<\/h4>\n<p>Mohammad R. Seyedsayamdost, Cyril S. Yee, JoAnne Stubbe<\/p>\n<h4>Abstract:<\/h4>\n<p>Escherichia coli ribonucleotide reductase is an \u03b12\u03b22 complex that catalyzes the conversion of nucleoside 5&prime;-diphosphates (NDPs) to deoxynucleotides (dNDPs). The active site for NDP reduction resides in \u03b12, and the essential diferric-tyrosyl radical (Y(122)(\u2022)) cofactor that initiates transfer of the radical to the active site cysteine in \u03b12 (C(439)), 35 \u00c5 removed, is in \u03b22. The oxidation is proposed to involve a hopping mechanism through aromatic amino acids (Y(122) \u2192 W(48) \u2192 Y(356) in \u03b22 to Y(731) \u2192 Y(730) \u2192 C(439) in \u03b12) and reversible proton-coupled electron transfer (PCET). Recently, 2,3,5-F(3)Y (F(3)Y) was site-specifically incorporated in place of Y(356) in \u03b22 and 3-NH(2)Y (NH(2)Y) in place of Y(731) and Y(730) in \u03b12. A pH-rate profile with F(3)Y(356)-\u03b22 suggested that as the pH is elevated, the rate-determining step of RNR can be altered from a conformational change to PCET and that the altered driving force for F(3)Y oxidation, by residues adjacent to it in the pathway, is responsible for this change. Studies with NH(2)Y(731(730))-\u03b12, \u03b22, CDP, and ATP resulted in detection of NH(2)Y radical (NH(2)Y(\u2022)) intermediates capable of dNDP formation. In this study, the reaction of F(3)Y(356)-\u03b22, \u03b12, CDP, and ATP has been examined by stopped-flow (SF) absorption and rapid freeze quench electron paramagnetic resonance spectroscopy and has failed to reveal any radical intermediates. The reaction of F(3)Y(356)-\u03b22, CDP, and ATP has also been examined with NH(2)Y(731)-\u03b12 (or NH(2)Y(730)-\u03b12) by SF kinetics from pH 6.5 to 9.2 and exhibited rate constants for NH(2)Y(\u2022) formation that support a change in the rate-limiting step at elevated pH. The results together with kinetic simulations provide a guide for future studies to detect radical intermediates in the pathway.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>DOI: 10.1021\/bi101319v Authors: Mohammad R. Seyedsayamdost, Cyril S. Yee, JoAnne Stubbe Abstract: Escherichia coli ribonucleotide reductase is an \u03b12\u03b22 complex that catalyzes the conversion of nucleoside 5&prime;-diphosphates (NDPs) to deoxynucleotides (dNDPs). The active site for NDP reduction resides in \u03b12, and the essential diferric-tyrosyl radical (Y(122)(\u2022)) cofactor that initiates transfer of the radical to the [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-640","post","type-post","status-publish","format-standard","hentry","category-freeze-quench"],"_links":{"self":[{"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=\/wp\/v2\/posts\/640","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=640"}],"version-history":[{"count":0,"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=\/wp\/v2\/posts\/640\/revisions"}],"wp:attachment":[{"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=640"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=640"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=640"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}