13C and 63,65Cu ENDOR studies of CO dehydrogenase from oligotropha carboxidovorans. Experimental evidence in support of a copper-carbonyl intermediate

Muralidharan Shanmugam, Jarett Wilcoxen, Diana Habel-Rodriguez, George E. Cutsail, Martin L. Kirk*, Brian M. Hoffman, Russ Hille

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

We report here an ENDOR study of an S = 1/2 intermediate state trapped during reduction of the binuclear Mo/Cu enzyme CO dehydrogenase by CO. ENDOR spectra of this state confirm that the 63,65Cu nuclei exhibits strong and almost entirely isotropic coupling to the unpaired electron, show that this coupling atypically has a positive sign, aiso = +148 MHz, and indicate an apparently undetectably small quadrupolar coupling. When the intermediate is generated using 13CO, coupling to the 13C is observed, with aiso = +17.3 MHz. A comparison with the couplings seen in related, structurally assigned Mo(V) species from xanthine oxidase, in conjunction with complementary computational studies, leads us to conclude that the intermediate contains a partially reduced Mo(V)/Cu(I) center with CO bound at the copper. Our results provide strong experimental support for a reaction mechanism that proceeds from a comparable complex of CO with fully oxidized Mo(VI)/Cu(I) enzyme.

Original languageEnglish (US)
Pages (from-to)17775-17782
Number of pages8
JournalJournal of the American Chemical Society
Volume135
Issue number47
DOIs
StatePublished - Nov 27 2013

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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