Panicco Paola, Astuti Yeni, Fantuzzi Andrea, Durrant James R, Gilardi Gianfranco
Division of Molecular Biosciences and Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ, UK.
J Phys Chem B. 2008 Nov 6;112(44):14063-8. doi: 10.1021/jp8050033. Epub 2008 Oct 9.
Cyclic voltabsorptometry is used for the first time to distinguish and characterize electrochemically the active (P450) and inactive (P420) forms of cytochromes P450 immobilized on an electrode during voltammetry experiments. This was achieved by using the heme domain (BMP) of the bacterial cytochrome P450 BM3 from Bacillus megaterium (CYP102A1) immobilized on mesopouros tin-oxide (SnO2) electrodes. We demonstrate that the formation of either the P450 form or the P420 one can be obtained by modifying the mesoporous electrode surface with polycations with different properties such as polyethylenimmine (PEI) and polydiallyldimethylammonium chloride (PDDA). Potential step spectroelectrochemistry allowed measurement of reduction potentials of the active P450 form. Values of -0.39+/-0.01 V and -0.58+/-0.01 V (both versus Ag/AgCl) were calculated for the active P450 form immobilized on the BMP/PDDA-SnO2 and BMP/PEI-SnO2 electrodes, respectively. The cyclic voltabsorptometric experiments showed how, when both the active and inactive forms are present on the PEI film, the inactive P420 species tends to dominate the cyclic voltammetric signal.
循环伏安吸收法首次用于在伏安法实验中对固定在电极上的细胞色素P450的活性（P450）和非活性（P420）形式进行电化学区分和表征。这是通过使用固定在介孔氧化锡（SnO2）电极上的巨大芽孢杆菌细菌细胞色素P450 BM3的血红素结构域（BMP）（CYP102A1）实现的。我们证明，通过用具有不同性质的聚阳离子（如聚乙烯亚胺（PEI）和聚二烯丙基二甲基氯化铵（PDDA））修饰介孔电极表面，可以获得P450形式或P420形式。电位阶跃光谱电化学法可测量活性P450形式的还原电位。对于固定在BMP/PDDA-SnO2和BMP/PEI-SnO2电极上的活性P450形式，计算得到的值分别为-0.39±0.01 V和-0.58±0.01 V（均相对于Ag/AgCl）。循环伏安吸收实验表明，当PEI膜上同时存在活性和非活性形式时，非活性P420物种如何倾向于主导循环伏安信号。
