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  Discovery of Dark pH-Dependent H(+) Migration in a [NiFe]-Hydrogenase and Its Mechanistic Relevance: Mobilizing the Hydrido Ligand of the Ni-C Intermediate

Murphy, B. J., Hidalgo, R., Roessler, M. M., Evans, R. M., Ash, P. A., Myers, W. K., et al. (2015). Discovery of Dark pH-Dependent H(+) Migration in a [NiFe]-Hydrogenase and Its Mechanistic Relevance: Mobilizing the Hydrido Ligand of the Ni-C Intermediate. Journal of the American Chemical Society, 137(26), 8484-8489. doi:10.1021/jacs.5b03182.

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Genre: Journal Article

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 Creators:
Murphy, Bonnie J.1, Author              
Hidalgo, Ricardo1, Author
Roessler, Maxie M.1, 2, Author
Evans, Rhiannon, M.1, Author
Ash, Philip A.1, Author
Myers, William K.1, 2, Author
Vincent, Kylie A.1, Author
Armstrong, Fraser A.1, Author
Affiliations:
1Department of Chemistry, University of Oxford, United Kingdom, ou_persistent22              
2Centre for Advanced Electron Spin Resonance, University of Oxford, United Kingdom, South Parks Road, OX1 3QR Oxford, United Kingdom, ou_persistent22              

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Free keywords: Charge transfer; Peptides and proteins; Ligands; Electron paramagnetic resonance spectroscopy; Cluster chemistry
 Abstract: Despite extensive studies on [NiFe]-hydrogenases, the mechanism by which these enzymes produce and activate H2 so efficiently remains unclear. A well-known EPR-active state produced under H2 and known as Ni-C is assigned as a NiIII-FeII species with a hydrido ligand in the bridging position between the two metals. It has long been known that low-temperature photolysis of Ni-C yields distinctive EPR-active states, collectively termed Ni-L, that are attributed to migration of the bridging-H species as a proton; however, Ni-L has mainly been regarded as an artifact with no mechanistic relevance. It is now demonstrated, based on EPR and infrared spectroscopic studies, that the Ni-C to Ni-L interconversion in Hydrogenase-1 (Hyd-1) from Escherichia coli is a pH-dependent process that proceeds readily in the dark-proton migration from Ni-C being favored as the pH is increased. The persistence of Ni-L in Hyd-1 must relate to unassigned differences in proton affinities of metal and adjacent amino acid sites, although the unusually high reduction potentials of the adjacent Fe-S centers in this O2-tolerant hydrogenase might also be a contributory factor, impeding elementary electron transfer off the [NiFe] site after proton departure. The results provide compelling evidence that Ni-L is a true, albeit elusive, catalytic intermediate of [NiFe]-hydrogenases.

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Language(s): eng - English
 Dates: 2015-03-262015-062015-06-232015-07-08
 Publication Status: Published in print
 Pages: 6
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1021/jacs.5b03182
 Degree: -

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Title: Journal of the American Chemical Society
  Other : JACS
  Abbreviation : J. Am. Chem. Soc.
Source Genre: Journal
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Publ. Info: Washington, DC : American Chemical Society
Pages: - Volume / Issue: 137 (26) Sequence Number: - Start / End Page: 8484 - 8489 Identifier: ISSN: 0002-7863
CoNE: https://pure.mpg.de/cone/journals/resource/954925376870