Mediated catalysis of Paracoccus pantotrophus cytochrome c peroxidase by P-pantotrophus pseudoazurin: kinetics of intermolecular electron transfer

Citation:
de Sousa, P. M. P., S. R. Pauleta, M. L. S. Goncalves, G. W. Pettigrew, I. Moura, M. M. C. dos Santos, and JJG Moura. "Mediated catalysis of Paracoccus pantotrophus cytochrome c peroxidase by P-pantotrophus pseudoazurin: kinetics of intermolecular electron transfer." Journal of Biological Inorganic Chemistry. 12 (2007): 691-698.

Abstract:

This work reports the direct electrochemistry of Paracoccus pantotrophus pseudoazurin and the mediated catalysis of cytochrome c peroxidase from the same organism. The voltammetric behaviour was examined at a gold membrane electrode, and the studies were performed in the presence of calcium to enable the peroxidase activation. A formal reduction potential, E (0)', of 230 +/- 5 mV was determined for pseudoazurin at pH 7.0. Its voltammetric signal presented a pH dependence, defined by pK values of 6.5 and 10.5 in the oxidised state and 7.2 in the reduced state, and was constant up to 1 M NaCl. This small copper protein was shown to be competent as an electron donor to cytochrome c peroxidase and the kinetics of intermolecular electron transfer was analysed. A second-order rate constant of 1.4 +/- 0.2 x 10(5) M(-1) s(-1) was determined at 0 M NaCl. This parameter has a maximum at 0.3 M NaCl and is pH-independent between pH 5 and 9.

Notes:

Times Cited: 9 de Sousa, P. M. Paes Pauleta, S. R. Goncalves, M. L. Simoes Pettigrew, G. W. Moura, I. dos Santos, M. M. Correia Moura, J. J. G.

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