Proton Transport in Clostridium pasteurianum (FeFe) Hydrogenase I: A Computational Study

Hai Long, Paul W. King, Christopher H. Chang

Research output: Contribution to journalArticlepeer-review

42 Scopus Citations

Abstract

To better understand the proton transport through the H2 production catalysts, the [FeFe] hydrogenases, we have undertaken a modeling and simulation study of the proton transfer processes mediated by amino acid side-chain residues in hydrogenase I from Clostridium pasteurianum. Free-energy calculation studies show that the side chains of two conserved glutamate residues, Glu-279 and Glu-282, each possess two stable conformations with energies that are sensitive to protonation state. Coordinated conformational changes of these residues can form a proton shuttle between the surface Glu-282 and Cys-299, which is the penultimate proton donor to the catalytic H-cluster. Calculated acid dissociation constants are consistent with a proton relay connecting the H-cluster to the bulk solution. The complete proton-transport process from the surface-disposed Glu-282 to Cys-299 is studied using coupled semiempirical quantum-mechanical/classical-mechanical dynamics. Two-dimensional free-energy maps show the mechanisms of proton transport, which involve Glu-279, Ser-319, and a short internal water relay to connect functionally Glu-282 with the H-cluster. The findings of conformational bistability, PT event coupling with pKa mismatch, and water participation have implications in the design of artificial water reduction or general electrocatalytic H 2-production catalysts.

Original languageAmerican English
Pages (from-to)890-900
Number of pages11
JournalJournal of Physical Chemistry B
Volume118
Issue number4
DOIs
StatePublished - 30 Jan 2014

NREL Publication Number

  • NREL/JA-2C00-60227

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