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

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

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Abstract / Description of output

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.

Original languageEnglish
Pages (from-to)691-698
Number of pages8
JournalJBIC Journal of Biological Inorganic Chemistry
Volume12
Issue number5
DOIs
Publication statusPublished - Jun 2007

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