Monovalent nickel in hydrogenase from Chromatium vinosum. Light sensitivity and evidence for direct interaction with hydrogen.
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 H2 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 2H2O is nearly 6-times slower than in H2O, 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.
van der Zwaan
J W
JW
Albracht
S P
SP
Fontijn
R D
RD
Slater
E C
EC
D002844:Chromatium / Q000201:enzymology*; D003903:Deuterium; D004578:Electron Spin Resonance Spectroscopy; D006859:Hydrogen; D006860:Hydrogen Bonding; D006864:Hydrogenase / Q000528:radiation effects; D008027:Light; D009532:Nickel / Q000528:radiation effects*; D010084:Oxidation-Reduction
D009532:Nickel; D006859:Hydrogen; D003903:Deuterium; D006864:Hydrogenase