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Monovalent nickel in hydrogenase from Chromatium vinosum
Author(s) -
van der Zwaan J.W.,
Albracht S.P.J.,
Fontijn R.D.,
Slater E.C.
Publication year - 1985
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(85)80533-0
Subject(s) - hydrogenase , nickel , chemistry , redox , photochemistry , photodissociation , metal , oxidation state , inorganic chemistry , coordination sphere , titration , hydrogen , crystallography , organic chemistry
Redox titrations with hydrogenase from Chromatium vinosum show that its nickel ion can exist in 3, possibly 4, different redox states: the 3 +, 2 +, 1 + and possibly a zero valent state. The 1 + state is unstable: oxidation to Ni(II) occurs unless H 2 gas is present. The Ni(I) coordination, but not that of Ni(III), is highly light sensitive. A photoreaction occurs on illumination. It is irreversible below 77 K, but reversible at 200 K. The rate of this photodissociation reaction in 2 H 2 O is nearly 6‐times slower than in H 2 O, indicating the breakage of a nickel‐hydrogen bond. This forms the first evidence for an H atom in the direct coordination sphere of Ni in hydrogenase and for the involvement of this metal in the reaction with hydrogen.