Direct Observation of an Iron-Bound Terminal Hydride in [FeFe]-Hydrogenase by Nuclear Resonance Vibrational Spectroscopy

Edward J. Reijerse, Cindy C. Pham, Vladimir Pelmenschikov, Ryan Gilbert-Wilson, Agnieszka Adamska-Venkatesh, Judith F. Siebel, Leland B. Gee, Yoshitaka Yoda, Kenji Tamasaku, Wolfgang Lubitz, Thomas B. Rauchfuss, Stephen P. Cramer

Research output: Contribution to journalArticlepeer-review

Abstract

[FeFe]-hydrogenases catalyze the reversible reduction of protons to molecular hydrogen with extremely high efficiency. The active site ("H-cluster") consists of a [4Fe-4S]H cluster linked through a bridging cysteine to a [2Fe]H subsite coordinated by CN- and CO ligands featuring a dithiol-amine moiety that serves as proton shuttle between the protein proton channel and the catalytic distal iron site (Fed). Although there is broad consensus that an iron-bound terminal hydride species must occur in the catalytic mechanism, such a species has never been directly observed experimentally. Here, we present FTIR and nuclear resonance vibrational spectroscopy (NRVS) experiments in conjunction with density functional theory (DFT) calculations on an [FeFe]-hydrogenase variant lacking the amine proton shuttle which is stabilizing a putative hydride state. The NRVS spectra unequivocally show the bending modes of the terminal Fe-H species fully consistent with widely accepted models of the catalytic cycle.

Original languageEnglish (US)
Pages (from-to)4306-4309
Number of pages4
JournalJournal of the American Chemical Society
Volume139
Issue number12
DOIs
StatePublished - Mar 29 2017

ASJC Scopus subject areas

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

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