Electron transfer by human wild-type and A287P mutant P450 oxidoreductase assessed by transient kinetics: Functional Basis of P450 Oxidoreductase Deficiency

We examined the POR mutant A287P, which is the most frequent cause of PORD in patients of European ancestry and partially disrupts most P450 activities in vitro.Flavin content analysis showed that A287P is deficient in FAD and FMN binding, although the mutation site is distant from the binding sites of both flavins. Externally added flavin partially restored the cytochrome c reductase activity of A287P, suggesting flavin therapy may be useful for this frequent form of POR deficiency. Transient kinetic dissection of the reaction of POR with NADPH and the reduction of cytochrome c by POR using stopped-flow techniques revealed defects in individual electron transfer steps mediated by A287P. A287P had impaired ability to accept electrons from NADPH, but was capable of a fast FMN → cytochrome c electron donation reaction. Thus the reduced rates of P450 activities with A287P may be due to deficient flavin and impaired electron transfer from NADPH.

Source: BJ Disease - March 2, 2015 Category: Biochemistry Authors: Y Jin, M Chen, T M Penning, W L Miller Tags: BJ Disease Source Type: research