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> so efficiently remains unclear. A well-known EPR-active state produced under H<sub>2</sub> and known as Ni-C is assigned as a N...
| Main Authors: | , , , , , , , |
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| Format: | Journal article |
| Language: | English |
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American Chemical Society
2015
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| _version_ | 1826304751618228224 |
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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> so efficiently remains unclear. A well-known EPR-active state produced under H<sub>2</sub> and known as Ni-C is assigned as a Ni<sup>III</sup>–Fe<sup>II</sup> 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 <em>Escherichia coli</em> 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 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> |
| first_indexed | 2024-03-07T06:22:32Z |
| format | Journal article |
| id | oxford-uuid:f32d59b2-57c6-495b-aeeb-f8a724e44b53 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T06:22:32Z |
| publishDate | 2015 |
| publisher | American Chemical Society |
| record_format | dspace |
| 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> so efficiently remains unclear. A well-known EPR-active state produced under H<sub>2</sub> and known as Ni-C is assigned as a Ni<sup>III</sup>–Fe<sup>II</sup> 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 <em>Escherichia coli</em> 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 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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