Nickel hydrogenases redox chemistry

Nickel is found in thiolate/sulflde environment in the [NiFe]-hydrogenases and in CODH/ACS.33 In addition, either a mononuclear Ni-thiolate site or a dinuclear cysteine-S bridged structure are assumed plausible for the new class of Ni-containing superoxide dismutases, NiSOD (A).34 [NiFe]-hydrogenase catalyzes the two-electron redox chemistry of dihydrogen. Several crystal structures of [NiFe]-hydrogenases have demonstrated that the active site of the enzyme consists of a heterodinuclear Ni—Fe unit bound to thiolate sulfurs of cysteine residues with a Ni—Fe distance below 3 A (4) 35-39 This heterodinuclear active site has been the target of extensive model studies, which are summarized in Section 6.3.4.12.5. 

Bagyinka, C., Whitehead, J. P., and Maroney, M. J., 1993, An X-ray absorption spectroscopic study of nickel redox chemistry in hydrogenase, J. Am. Chem. Soc. 115 3576n3585. 

Albracht SPJ, van derZwaan JW, Fontijn RD, Slater EC (1986) On the possible redox states of nickel and the iron-sulphur cluster in hydrogenase from Chromatium vinosum. In Xavier AV (ed) Frontiers in bioinorganic Chemistry. VCH, Weinheim, pp 11-19... 

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