Tert-Butylphenylacetylene is a potent mechanism-based inactivator of cytochrome P450 2B4: inhibition of cytochrome P450 catalysis by steric hindrance.

ABSTRACT: We have demonstrated that 4-(tert-butyl)-phenylacetylene (tBPA) is a potent mechanism-based inactivator for cytochrome P450 2B4 (P450 2B4) in the reconstituted system. It inactivates P450 2B4 in a NADPH- and time-dependent manner with a K(I) of 0.44 microM and k(inact) of 0.12 min(-1). The partition ratio was approximately zero, indicating that inactivation occurs without the reactive intermediate leaving the active site. Liquid chromatography-mass spectrometry analyses revealed that tBPA forms a protein adduct with a 1:1 stoichiometry. Peptide mapping of the tBPA-modified protein provides evidence that tBPA is covalently bound to Thr302. This is consistent with results of molecular modeling that show the terminal carbon of the acetylenic group is only 3.65 A away from Thr302. To character

SUBMITTER: Zhang H 

PROVIDER: S-EPMC2774989 | biostudies-literature | 2009 Nov

REPOSITORIES: biostudies-literature