Mediated catalysis of Paracoccus pantotrophus cytochrome c peroxidase by P-pantotrophus pseudoazurin:: kinetics of intermolecular electron transfer
Mediated catalysis of Paracoccus pantotrophus cytochrome c peroxidase by P-pantotrophus pseudoazurin:: kinetics of intermolecular electron transfer
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DOI：
10.1007/s00775-007-0219-9
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发表时间：
2007-06-01
影响因子：
3
通讯作者：
Moura, J. J. G.
中科院分区：
文献类型：
--
作者：
de Sousa, P. M. Paes;Pauleta, S. R.;Moura, J. J. G.
本文报道了嗜食副球菌的直接电化学和细胞色素c过氧化物酶的介导催化作用。在金膜电极上检查伏安行为，并且在钙的存在下进行研究以使过氧化物酶活化。在pH7.0时，假天青的形式还原电位E（0 mV）为230 +/-5 mV。其伏安信号呈现pH依赖性，由氧化状态下的pK值为6.5和10.5以及还原状态下的pK值为7.2定义，并且在高达1 M NaCl时是恒定的。这种小铜蛋白被证明是主管作为电子供体细胞色素c过氧化物酶和分子间电子转移的动力学进行了分析。在0 M NaCl下测定的二级速率常数为1.4 +/- 0.2 x 10（5）M-1 s（-1）。该参数在0.3 M NaCl下具有最大值，并且在pH 5和9之间与pH无关。
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.