Discovery of dark pH-dependent H+ migration in a [NiFe]-hydrogenase and its mechanistic relevance: mobilizing the hydrido ligand of the Ni-C intermediate

<p>Despite extensive studies on [NiFe]-hydrogenases, the mechanism by which these enzymes produce and activate H<sub>2</sub>&nbsp;so efficiently remains unclear. A well-known EPR-active state produced under H<sub>2</sub>&nbsp;and known as Ni-C is assigned as a N...

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मुख्य लेखकों: Murphy, BJ, Hidalgo, R, Roessler, MM, Evans, RM, Ash, PA, Myers, WK, Vincent, KA, Armstrong, FA
स्वरूप: Journal article
भाषा:English
प्रकाशित: American Chemical Society 2015
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author Murphy, BJ
Hidalgo, R
Roessler, MM
Evans, RM
Ash, PA
Myers, WK
Vincent, KA
Armstrong, FA
author_facet Murphy, BJ
Hidalgo, R
Roessler, MM
Evans, RM
Ash, PA
Myers, WK
Vincent, KA
Armstrong, FA
author_sort Murphy, BJ
collection OXFORD
description <p>Despite extensive studies on [NiFe]-hydrogenases, the mechanism by which these enzymes produce and activate H<sub>2</sub>&nbsp;so efficiently remains unclear. A well-known EPR-active state produced under H<sub>2</sub>&nbsp;and known as Ni-C is assigned as a Ni<sup>III</sup>&ndash;Fe<sup>II</sup>&nbsp;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&nbsp;<em>Escherichia coli</em>&nbsp;is a pH-dependent process that proceeds readily in the dark&mdash;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&ndash;S centers in this O<sub>2</sub>-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.</p>
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spelling oxford-uuid:f32d59b2-57c6-495b-aeeb-f8a724e44b532022-03-27T12:10:01ZDiscovery of dark pH-dependent H+ migration in a [NiFe]-hydrogenase and its mechanistic relevance: mobilizing the hydrido ligand of the Ni-C intermediateJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:f32d59b2-57c6-495b-aeeb-f8a724e44b53EnglishSymplectic ElementsAmerican Chemical Society2015Murphy, BJHidalgo, RRoessler, MMEvans, RMAsh, PAMyers, WKVincent, KAArmstrong, FA<p>Despite extensive studies on [NiFe]-hydrogenases, the mechanism by which these enzymes produce and activate H<sub>2</sub>&nbsp;so efficiently remains unclear. A well-known EPR-active state produced under H<sub>2</sub>&nbsp;and known as Ni-C is assigned as a Ni<sup>III</sup>&ndash;Fe<sup>II</sup>&nbsp;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&nbsp;<em>Escherichia coli</em>&nbsp;is a pH-dependent process that proceeds readily in the dark&mdash;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&ndash;S centers in this O<sub>2</sub>-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.</p>
spellingShingle Murphy, BJ
Hidalgo, R
Roessler, MM
Evans, RM
Ash, PA
Myers, WK
Vincent, KA
Armstrong, FA
Discovery of dark pH-dependent H+ migration in a [NiFe]-hydrogenase and its mechanistic relevance: mobilizing the hydrido ligand of the Ni-C intermediate
title Discovery of dark pH-dependent H+ migration in a [NiFe]-hydrogenase and its mechanistic relevance: mobilizing the hydrido ligand of the Ni-C intermediate
title_full Discovery of dark pH-dependent H+ migration in a [NiFe]-hydrogenase and its mechanistic relevance: mobilizing the hydrido ligand of the Ni-C intermediate
title_fullStr Discovery of dark pH-dependent H+ migration in a [NiFe]-hydrogenase and its mechanistic relevance: mobilizing the hydrido ligand of the Ni-C intermediate
title_full_unstemmed Discovery of dark pH-dependent H+ migration in a [NiFe]-hydrogenase and its mechanistic relevance: mobilizing the hydrido ligand of the Ni-C intermediate
title_short Discovery of dark pH-dependent H+ migration in a [NiFe]-hydrogenase and its mechanistic relevance: mobilizing the hydrido ligand of the Ni-C intermediate
title_sort discovery of dark ph dependent h migration in a nife hydrogenase and its mechanistic relevance mobilizing the hydrido ligand of the ni c intermediate
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