Abstract |
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-SI(r), provides the link between fully oxidized (Ni-A, Ni-B) and active (Ni-SI(a), Ni-C and Ni-R) forms of hydrogenase. In this work Ni-SI(r) was found to be light-sensitive (T <or= 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-SI(1961)). Rapid scan kinetic infrared measurements provided activation energies for the transition from Ni-SL to Ni-SI(r) 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-SI(r) 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 (Ni(2+)). In addition, at T <or= 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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Authors | Maria-Eirini Pandelia, Hideaki Ogata, Leslie J Currell, Marco Flores, Wolfgang Lubitz |
Journal | Journal of biological inorganic chemistry : JBIC : a publication of the Society of Biological Inorganic Chemistry
(J Biol Inorg Chem)
Vol. 14
Issue 8
Pg. 1227-41
(Nov 2009)
ISSN: 1432-1327 [Electronic] Germany |
PMID | 19626348
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Bacterial Proteins
- Isotopes
- Nickel
- Carbon Monoxide
- nickel-iron hydrogenase
- Hydrogenase
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Topics |
- Bacterial Proteins
(chemistry, metabolism)
- Carbon Monoxide
(metabolism)
- Desulfovibrio vulgaris
(enzymology)
- Enzyme Activation
- Hydrogen Bonding
- Hydrogenase
(chemistry, metabolism)
- Isotopes
(metabolism)
- Light
- Models, Molecular
- Nickel
(metabolism)
- Oxidation-Reduction
- Protein Conformation
- Spectrophotometry, Infrared
- Spectroscopy, Fourier Transform Infrared
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