10.1021\/acscatal.3c01781<\/a><\/p>\nAuthors:<\/h4>\n
Carola S. Seelmann, Simona G. Huwiler, Martin Culka, Marc J. F. Strampraad, Till Biskup, Stefan Weber, G. Matthias Ullmann, Volker Sch\u00fcnemann, Peter\u2010Leon Hagedoorn, Antonio J. Pierik, Matthias Boll<\/p>\n
Abstract:<\/h4>\n
The Birch reduction is a widely used synthetic tool to reduce arenes to 1,4-cyclohexadienes. Its harsh cryogenic reaction conditions and the dependence on alkali metals have motivated researchers to explore alternative approaches. In anaerobic aromatic compound degrading microbes, class II benzoyl-coenzyme A (CoA) reductases (BCRs) reduce benzoyl-CoA to the conjugated cyclohexa-1,5-diene-1-carboxyl-CoA (1,5-dienoyl-CoA) at a tungsten-bis-metallopterin (MPT) cofactor. Though previous structure-based computational studies were in favor of a Birch-like reduction via W(V)\/radical intermediates, any experimental evidence for such a mechanism was lacking. Here, we combined freeze-quench and equilibrium electron paramagnetic resonance (EPR) spectroscopic analyses in H2O, D2O, and H217O with redox titrations using wild-type and molecular variants of the catalytic BamB subunit of class II BCR from the anaerobic bacterium Geobacter metallireducens. We provide spectroscopic evidence for a kinetically competent radical\/W(V)\u2013OH intermediate obtained after hydrogen atom transfer from the W-aqua-ligand to the aromatic ring and for an invariant histidine as a proton donor assisting the second electron transfer. Quantum mechanical\/molecular mechanical calculations suggest that the unique tetrahydro state of both pyranopterins is essential for the reversibility of enzymatic Birch reduction. This work elucidates nature\u2019s solution for the chemically demanding Birch reduction and demonstrates how the reactivity of MPT cofactors can be expanded to highly challenging radical chemistry at the negative limit of the biological redox window.<\/p>\n","protected":false},"excerpt":{"rendered":"
DOI: 10.1021\/acscatal.3c01781 Authors: Carola S. Seelmann, Simona G. Huwiler, Martin Culka, Marc J. F. Strampraad, Till Biskup, Stefan Weber, G. Matthias Ullmann, Volker Sch\u00fcnemann, Peter\u2010Leon Hagedoorn, Antonio J. Pierik, Matthias Boll Abstract: The Birch reduction is a widely used synthetic tool to reduce arenes to 1,4-cyclohexadienes. Its harsh cryogenic reaction conditions and the dependence on […]<\/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-749","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\/749","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=749"}],"version-history":[{"count":0,"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=\/wp\/v2\/posts\/749\/revisions"}],"wp:attachment":[{"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=749"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=749"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=749"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}