TY - JOUR
T1 - Mediated catalysis of Paracoccus pantotrophus cytochrome c peroxidase by P-pantotrophus pseudoazurin: kinetics of intermolecular electron transfer
AU - Paes de Sousa, P. M.
AU - Pauleta, S. R.
AU - Goncalves, M. L. Simoes
AU - Pettigrew, G. W.
AU - Moura, I.
AU - dos Santos, M. M. Correia
AU - Moura, J. J. G.
PY - 2007/6
Y1 - 2007/6
N2 - 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.
AB - 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.
U2 - 10.1007/s00775-007-0219-9
DO - 10.1007/s00775-007-0219-9
M3 - Article
SN - 0949-8257
VL - 12
SP - 691
EP - 698
JO - JBIC Journal of Biological Inorganic Chemistry
JF - JBIC Journal of Biological Inorganic Chemistry
IS - 5
ER -