The thermodynamics and kinetics of electron transfer in the cytochrome P450cam enzyme system
- 28 May 1999
- journal article
- review article
- Published by Wiley in FEBS Letters
- Vol. 451 (3) , 351-353
- https://doi.org/10.1016/s0014-5793(99)00610-9
Abstract
In anaerobic environments the first electron transfer in substrate-free P450cam 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 P450cam compared to substrate-bound P450cam. The ferric haem centre in substrate-free P450cam changes from six co-ordinate to five co-ordinate when reduced whereas in substrate-bound P450cam the iron centre remains five co-ordinate in both oxidation states. The slower rate of electron transfer in the substrate-free P450cam is therefore attributed to a larger reorganisation energy as predicted by Marcus theory.Keywords
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