Identification of a Catalytic Iron-Hydride at the H-Cluster of [FeFe]-Hydrogenase

David W. Mulder, Yisong Guo, Michael W. Ratzloff, Paul W. King

Research output: Contribution to journalArticlepeer-review

112 Scopus Citations

Abstract

Hydrogenases couple electrochemical potential to the reversible chemical transformation of H2 and protons, yet the reaction mechanism and composition of intermediates are not fully understood. In this Communication we describe the biophysical properties of a hydride-bound state (Hhyd) of the [FeFe]-hydrogenase from Chlamydomonas reinhardtii. The catalytic H-cluster of [FeFe]-hydrogenase consists of a [4Fe-4S] subcluster ([4Fe-4S]H) linked by a cysteine thiol to an azadithiolate-bridged 2Fe subcluster ([2Fe]H) with CO and CN-ligands. Mossbauer analysis and density functional theory (DFT) calculations show that Hhyd consists of a reduced [4Fe-4S]H+ coupled to a diferrous [2Fe]H with a terminally bound Fe-hydride. The existence of the Fe-hydride in Hhyd was demonstrated by an unusually low Mossbauer isomer shift of the distal Fe of the [2Fe]H subcluster. A DFT model of Hhyd shows that the Fe-hydride is part of a H-bonding network with the nearby bridging azadithiolate to facilitate fast proton exchange and catalytic turnover.

Original languageAmerican English
Pages (from-to)83-86
Number of pages4
JournalJournal of the American Chemical Society
Volume139
Issue number1
DOIs
StatePublished - 11 Jan 2017

Bibliographical note

Publisher Copyright:
© 2016 American Chemical Society.

NREL Publication Number

  • NREL/JA-2700-67578

Keywords

  • [FeFe]-hydrogenase
  • Chlamydomonas reinhardtii
  • electrochemical potential

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