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Hydrogen activation by [NiFe]-hydrogenases

Hydrogen activation by [NiFe]-hydrogenases

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Authors

  • Stephen B. Carr (Lead / Corresponding author)
  • Rhiannon M. Evans
  • Emily J. Brooke
  • Sara A. M. Wehlin
  • Elena Nomerotskaia
  • Frank Sargent
  • Fraser A. Armstrong (Lead / Corresponding author)
  • Simon E. V. Phillips (Lead / Corresponding author)

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Info

Original languageEnglish
Pages (from-to)863-868
Number of pages6
JournalBiochemical Society Transactions
Volume44
Issue number3
Early online date9 Jun 2016
DOIs
StatePublished - 15 Jun 2016

Abstract

Hydrogenase-1 (Hyd-1) from Escherichia coli is a membrane-bound enzyme that catalyses the reversible oxidation of molecular H2 The active site contains one Fe and one Ni atom and several conserved amino acids including an arginine (Arg(509)), which interacts with two conserved aspartate residues (Asp(118) and Asp(574)) forming an outer shell canopy over the metals. There is also a highly conserved glutamate (Glu(28)) positioned on the opposite side of the active site to the canopy. The mechanism of hydrogen activation has been dissected by site-directed mutagenesis to identify the catalytic base responsible for splitting molecular hydrogen and possible proton transfer pathways to/from the active site. Previous reported attempts to mutate residues in the canopy were unsuccessful, leading to an assumption of a purely structural role. Recent discoveries, however, suggest a catalytic requirement, for example replacing the arginine with lysine (R509K) leaves the structure virtually unchanged, but catalytic activity falls by more than 100-fold. Variants containing amino acid substitutions at either or both, aspartates retain significant activity. We now propose a new mechanism: heterolytic H2 cleavage is via a mechanism akin to that of a frustrated Lewis pair (FLP), where H2 is polarized by simultaneous binding to the metal(s) (the acid) and a nitrogen from Arg(509) (the base).

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  • Author Accepted Manuscript

    Accepted author manuscript, 822 KB, PDF-document

    This is the peer-reviewed accepted manuscript. The final published version of this article is published in Biochemical Society Transactions 44:3 (2016): 863-68.

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