Short-lived neutral FMN and FAD semiquinones are transient intermediates in cryo-reduced yeast NADPH-cytochrome P450 reductase.

ABSTRACT: The electron configuration of flavin cofactors, FMN and FAD, is a critical factor governing the reactivity of NADPH-cytochrome P450 reductase (CPR). The current view of electron transfer by the mammalian CPR, based on equilibrium redox potentials of the flavin cofactors, is that the two electron-reduced FMN hydroquinone (FMNH2), rather than one electron-reduced FMN semiquinone, serves as electron donor to the terminal protein acceptors. However, kinetic and thermodynamic studies on the CPR species originated from different organisms have shown that redox potentials measured at distinct electron transfer steps differ from redox potentials determined by equilibrium titration. Collectively, previous observations suggest that the short-lived transient semiquinone species may carry electrons in

SUBMITTER: Davydov RM 

PROVIDER: S-EPMC7575000 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature