Magnetic interaction of nickel(III) and the iron-sulphur cluster in hydrogenase from Chromatium vinosum |
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Authors: | SPJ Albracht ML Kalkman EC Slater |
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Institution: | Laboratory of Biochemistry, B.C.P. Jansen Institute, University of Amsterdam, P.O. Box 20151, 1000 HD Amsterdam The Netherlands |
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Abstract: | Upon partial reduction of hydrogenase from Chromatium vinosum with ascorbate plus phenazine methosulphate, EPR signals due to Ni(III) and a 3Fe-xS] cluster appear simultaneously and with equal intensities. Since the intact enzyme shows no signals, it is concluded that Ni(III) and a 4Fe-4S]3+ cluster interact magnetically in such a way as to prevent the detection of the two paramagnets as individual systems. This interaction is thought to be the origin of a signal in which Fe is involved and which is not due to an system (Albracht, S.P.J., Albrecht-Ellmer, K.J., Schmedding, D.J.M. and Slater, E.C. (1982) Biochim. Biophys. Acta 681, 330–334). A variable fraction of the enzyme preparation shows signals due to Ni(III) and a 3Fe-xS] cluster with equal intensities without any further treatment. These are thought to be derived from irreversibly inactivated enzyme molecules. The enzyme contains no selenium. |
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Keywords: | Hydrogenase Nickel(III) Iron-sulfur cluster ESR (C vinosum) TMPD Hipip high-potential Fe-S protein |
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