Quantum mechanical study of putative intermediates in adduct formation by the suicide substrate ethylene with cytochrome P-450

Abstract

We report INDO calculations on putative intermediates in the oxidative metabolism of ethylene by cytochrome P-450 leading to either the epoxide or the formation of an adduct at the pyrrole nitrogen of the porphyrin. We also report the characterization of a ferryl model which has been postulated to be the active oxygen state involved in oxidation reactions involving cytochrome P-450. Our results suggest that adduct formation proceeds via a radical process which leaves the oxygen bound to the iron forming a five-membered cyclic structure. The possibility of an intermediate which could lead to either the epoxide or the N-alkylated porphyrin is discussed.