title: EPR of a novel high-spin component in activated hydrogenase from Desulfovibrio vulgaris (Hildenborough).
abstract: The EPR of reoxidized hydrogenase from Desulfovibrio vulgaris (H.) has been reinvestigated. In contrast to other workers [(1984) Proc. Natl. Acad. Sci. USA 81, 3728-3732] we find the axial signal with g = 2.06; 2.01 to be only a minor component of concentration 0.03 spin/mol. In the spectrum of fully active reoxidized enzyme this signal is overshadowed by a rhombic signal (0.1 spin/mol) with g = 2.11; 2.05; 2.00 reminiscent of the only signal found for other oxidized bidirectional hydrogenases. In addition, a novel signal has been detected with geff = 5.0 which, under the assumptions that S = 2 and [delta ms] = 2, quantitates to roughly one spin/mol. Ethylene glycol affects the relative intensity of the different signals. It is suggested that O2 sensitization parallels a spin-state transition of an iron-sulfur cluster.
mesh_terms: D003901:Desulfovibrio / Q000201:enzymology*; D004578:Electron Spin Resonance Spectroscopy; D004789:Enzyme Activation; D006864:Hydrogenase; D007506:Iron-Sulfur Proteins; D010084:Oxidation-Reduction
chemical_list: D007506:Iron-Sulfur Proteins; D006864:Hydrogenase