期刊
JOURNAL OF BIOLOGICAL INORGANIC CHEMISTRY
卷 14, 期 8, 页码 1227-1241出版社
SPRINGER
DOI: 10.1007/s00775-009-0566-9
关键词
[NiFe] hydrogenase; Desulfovibrio vulgaris; Rapid scan Fourier transform infrared; Light sensitivity; Activation energies; Isotope effect; Wavelength dependence; Carbon monoxide
资金
- Max Planck Society [212508]
- BMFT
The [NiFe] hydrogenase from the sulphate-reducing bacterium Desulfovibrio vulgaris Miyazaki F is reversibly inhibited in the presence of molecular oxygen. A key intermediate in the reactivation process, Ni-SIr, provides the link between fully oxidized (Ni-A, Ni-B) and active (Ni-SIa, Ni-C and Ni-R) forms of hydrogenase. In this work Ni-SIr was found to be light-sensitive (T a parts per thousand currency sign 110 K), similar to the active Ni-C and the CO-inhibited states. Transition to the final photoproduct state (Ni-SL) was shown to involve an additional transient light-induced state (Ni-SI1961). Rapid scan kinetic infrared measurements provided activation energies for the transition from Ni-SL to Ni-SIr in protonated as well as in deuterated samples. The inhibitor CO was found not to react with the active site of the Ni-SL state. The wavelength dependence of the Ni-SIr photoconversion was examined in the range between 410 and 680 nm. Light-induced effects were associated with a nickel-centred electronic transition, possibly involving a change in the spin state of nickel (Ni2+). In addition, at T a parts per thousand currency sign 40 K the CN- stretching vibrations of Ni-SL were found to be dependent on the colour of the monochromatic light used to irradiate the species, suggesting a change in the interaction of the hydrogen-bonding network of the surrounding amino acids. A possible mechanism for the photochemical process, involving displacement of the oxygen-based ligand, is discussed.
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