The thermodynamics and kinetics of electron transfer in the cytochrome P450cam enzyme system

FEBS Letters

Wong, Luet-Lok¹  Hill, H.Allen O¹  Honeychurch, Michael J¹ 

[1] Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR, UK

关键词: Monooxygenase;    P450;    Electron transfer;    Redox potential;    Oxygen binding;   

DOI  :  10.1016/S0014-5793(99)00610-9

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

In anaerobic environments the first electron transfer in substrate-free P450_cam is known to be thermodynamically unfavourable, but in the presence of dioxygen the reduction potential for the reaction shifts positively to make electron transfer thermodynamically favourable. Nevertheless a slower rate of electron transfer is observed in the substrate-free P450_cam compared to substrate-bound P450_cam. The ferric haem centre in substrate-free P450_cam changes from six co-ordinate to five co-ordinate when reduced whereas in substrate-bound P450_cam the iron centre remains five co-ordinate in both oxidation states. The slower rate of electron transfer in the substrate-free P450_cam is therefore attributed to a larger reorganisation energy as predicted by Marcus theory.

【 授权许可】

Unknown