{"id":701,"date":"2026-04-15T13:26:41","date_gmt":"2026-04-15T13:26:41","guid":{"rendered":"https:\/\/citations.tools.bio-logic.fr\/?p=701"},"modified":"2026-04-15T13:26:41","modified_gmt":"2026-04-15T13:26:41","slug":"probing-the-reaction-mechanism-of-the-d-ala-d-ala-dipeptidase-vanx-by-using-stopped-flow-kinetic-and-rapid-freeze-quench-epr-studies-on-the-coii-substituted-enzyme","status":"publish","type":"post","link":"https:\/\/citations.tools.bio-logic.fr\/?p=701","title":{"rendered":"Probing the Reaction Mechanism of the <scp>d<\/scp>-ala-<scp>d<\/scp>-ala Dipeptidase, VanX, by Using Stopped-Flow Kinetic and Rapid-Freeze Quench EPR Studies on the Co(II)-Substituted Enzyme"},"content":{"rendered":"<h4>DOI:<\/h4>\n<p><a href=\"https:\/\/doi.org\/10.1021\/ja0627343\" target=\"_blank\" rel=\"noopener\">10.1021\/ja0627343<\/a><\/p>\n<h4>Authors:<\/h4>\n<p>Megan L. Matthews, Gopalraj Periyannan, Christine E. Hajdin, Tara K. Sidgel, Brian Bennett, Michael W. Crowder<\/p>\n<h4>Abstract:<\/h4>\n<p>In an effort to probe the reaction mechanism of VanX, the d-ala-d-ala dipeptidase required for high-level vancomycin resistance in bacteria, stopped-flow kinetic and rapid-freeze quench EPR studies were conducted on the Co(II)-substituted enzyme when reacted with d-ala-d-ala. The intensity of the Co(II) ligand field band at 550 nm decreased (epsilon550 = 140 to 18 M-1 cm-1) when VanX was reacted with substrate, suggesting that the coordination number of the metal increases from 5 to 6 upon substrate binding. The stopped-flow trace was fitted to a kinetic mechanism that suggests the presence of an intermediate whose breakdown is rate-limiting. Rapid-freeze quench EPR studies verified the presence of a reaction intermediate that exhibits an unusually low hyperfine constant (33 G), which suggests a bidentate coordination of the intermediate to the metal center. The EPR studies also identified a distinct enzyme product complex. The results were used to offer a detailed reaction mechanism for VanX that can be used to guide future inhibitor design efforts.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>DOI: 10.1021\/ja0627343 Authors: Megan L. Matthews, Gopalraj Periyannan, Christine E. Hajdin, Tara K. Sidgel, Brian Bennett, Michael W. Crowder Abstract: In an effort to probe the reaction mechanism of VanX, the d-ala-d-ala dipeptidase required for high-level vancomycin resistance in bacteria, stopped-flow kinetic and rapid-freeze quench EPR studies were conducted on the Co(II)-substituted enzyme when reacted [&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-701","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\/701","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=701"}],"version-history":[{"count":0,"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=\/wp\/v2\/posts\/701\/revisions"}],"wp:attachment":[{"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=701"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=701"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=701"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}