| http://purl.uniprot.org/citations/30070475 | http://www.w3.org/1999/02/22-rdf-syntax-ns#type | http://purl.uniprot.org/core/Journal_Citation |
| http://purl.uniprot.org/citations/30070475 | http://www.w3.org/2000/01/rdf-schema#comment | "Catalytic long-range proton transfer in [NiFe]-hydrogenases has long been associated with a highly conserved glutamate (E) situated within 4 Å of the active site. Substituting for glutamine (Q) in the O2-tolerant [NiFe]-hydrogenase-1 from Escherichia coli produces a variant (E28Q) with unique properties that have been investigated using protein film electrochemistry, protein film infrared electrochemistry, and X-ray crystallography. At pH 7 and moderate potential, E28Q displays approximately 1% of the activity of the native enzyme, high enough to allow detailed infrared measurements under steady-state conditions. Atomic-level crystal structures reveal partial displacement of the amide side chain by a hydroxide ion, the occupancy of which increases with pH or under oxidizing conditions supporting formation of the superoxidized state of the unusual proximal [4Fe-3S] cluster located nearby. Under these special conditions, the essential exit pathway for at least one of the H+ ions produced by H2 oxidation, and assumed to be blocked in the E28Q variant, is partially repaired. During steady-state H2 oxidation at neutral pH (i.e., when the barrier to H+ exit via Q28 is almost totally closed), the catalytic cycle is dominated by the reduced states "Nia-R" and "Nia-C", even under highly oxidizing conditions. Hence, E28 is not involved in the initial activation/deprotonation of H2, but facilitates H+ exit later in the catalytic cycle to regenerate the initial oxidized active state, assumed to be Nia-SI. Accordingly, the oxidized inactive resting state, "Ni-B", is not produced by E28Q in the presence of H2 at high potential because Nia-SI (the precursor for Ni-B) cannot accumulate. The results have important implications for understanding the catalytic mechanism of [NiFe]-hydrogenases and the control of long-range proton-coupled electron transfer in hydrogenases and other enzymes."xsd:string |
| http://purl.uniprot.org/citations/30070475 | http://purl.org/dc/terms/identifier | "doi:10.1021/jacs.8b04798"xsd:string |
| http://purl.uniprot.org/citations/30070475 | http://purl.uniprot.org/core/author | "Armstrong F.A."xsd:string |
| http://purl.uniprot.org/citations/30070475 | http://purl.uniprot.org/core/author | "Evans R.M."xsd:string |
| http://purl.uniprot.org/citations/30070475 | http://purl.uniprot.org/core/author | "Carr S.B."xsd:string |
| http://purl.uniprot.org/citations/30070475 | http://purl.uniprot.org/core/author | "Vincent K.A."xsd:string |
| http://purl.uniprot.org/citations/30070475 | http://purl.uniprot.org/core/author | "Beaton S.E."xsd:string |
| http://purl.uniprot.org/citations/30070475 | http://purl.uniprot.org/core/author | "Brooke E.J."xsd:string |
| http://purl.uniprot.org/citations/30070475 | http://purl.uniprot.org/core/author | "Ash P.A."xsd:string |
| http://purl.uniprot.org/citations/30070475 | http://purl.uniprot.org/core/date | "2018"xsd:gYear |
| http://purl.uniprot.org/citations/30070475 | http://purl.uniprot.org/core/name | "J Am Chem Soc"xsd:string |
| http://purl.uniprot.org/citations/30070475 | http://purl.uniprot.org/core/pages | "10208-10220"xsd:string |
| http://purl.uniprot.org/citations/30070475 | http://purl.uniprot.org/core/title | "Mechanistic Exploitation of a Self-Repairing, Blocked Proton Transfer Pathway in an O2-Tolerant [NiFe]-Hydrogenase."xsd:string |
| http://purl.uniprot.org/citations/30070475 | http://purl.uniprot.org/core/volume | "140"xsd:string |
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