Rapid kinetic methods to dissect steroidogenic cytochrome P450 reaction mechanisms

Mechanisms of reaction in cytochrome P450: Hydroxylation of camphor in P450cam.

The fundamental nature of reactivity in cytochrome P450 enzymes is currently controversial. Modelling of bacterial P450cam has suggested an important role for the haem propionates in the catalysis, though this finding has been questioned. Understanding the mechanisms of this enzyme family is important both in terms of basic biochemistry and potentially in the prediction of drug metabolism. We h...

Cytochrome b5 inhibits electron transfer from NADPH-cytochrome P450 reductase to ferric cytochrome P450 2B4.

Experiments demonstrating that cytochrome (cyt) b5 inhibits the activity of cytochrome P450 2B4 (cyt P450 2B4) at higher concentrations suggested that cyt b5 was occupying the cyt P450 reductase-binding site on cyt P450 2B4 and preventing the reduction of ferric cyt P450 (Zhang, H., Im, S.-C., and Waskell, L. (2007) J. Biol. Chem. 282, 29766-29776). In this work experiments were undertaken with...

Cytochrome P450 2c8 Reaction Phenotyping: Substrate Selection and Inhibition Profile

Metabolic profiling and cytochrome P450 reaction phenotyping of medroxyprogesterone acetate.

Medroxyprogesterone acetate (MPA) is one of the most frequently prescribed progestins for conception, hormone replacement therapy, and adjuvant endocrine therapy. MPA has a low oral bioavailability because of extensive metabolism; however, its metabolism was poorly documented. This study was intended to profile the phase I metabolites of MPA and the cytochrome P450 (P450) isoforms involved. Aft...

Rapid and reliable method for cytochrome P450 2D6 genotyping.

BACKGROUND Single-nucleotide polymorphisms and single-base deletions within the cytochrome P450 2D6 (CYP2D6) gene have been associated with a poor metabolizer (PM) phenotype and display a frequency of 7-10% in the Caucasian population. METHODS We developed a reliable and rapid procedure to identify five major PM-associated mutations (CYP2D6*4, *7, and *8) and deletions (CYP2D6*3 and *6) by re...