The thermostable hydrogenase from Thiocapsa roseopersicina was examined by low‐temperature ESR spectroscopy. Two types of signals were detected, from an oxidized iron‐sulphur cluster and a nickel centre (Ni‐A). In the oxidized protein additional signals were observed due to spin‐spin interaction between the two paramagnetic centres. This interaction could be reversibly abolished by reduction to a redox potential below 105 mV. This implies that an additional redox centre is involved in the interaction, for which an Fe3+ ion is suggested. Reduction with hydrogen induced a second type of nickel ESR signal (Ni‐C), corresponding to an intermediate redox state seen in other nickel hydrogenases. The Ni‐C species was light‐sensitive at cryogenic temperatures. At temperatures near to 4.2 K the Ni‐C signal showed evidence of interaction with another paramagnetic centre, presumably a second iron‐sulphur cluster. On reoxidation a signal due to a third Ni(III) species, Ni‐B, increased in amplitude. These results establish that metal centres in the hydrogenase from T. roseopersicina are closely similar to those of the well‐studied hydrogenase from Chromatium vinosum.
|Number of pages||6|
|Journal||European Journal of Biochemistry|
|Publication status||Published - Jun 1989|
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