Multiplicity of n‐heptane oxidation pathways catalyzed by cytochrome P450

Abstract

Modeling, mutagenesis, and kinetic studies have demonstrated that the substrate-binding site of cytochrome P450 is composed of multiple interactive regions that are capable of simultaneously binding two or more xenobiotics. Substrate molecules can interact with each other after docking. Thus, substrates can compete for the activated oxygen-ferrous complex or alter the spatial orientation of other molecules. Cytochrome P450 is a unique enzyme that produces n-heptane metabolites of different oxidation states. Metabolism of n-heptane was investigated with rat liver microsomes and a reconstituted rat liver system. Ethanol, n-propanol, and n-butanol molecules interacted with the n-heptane molecule and resulted in cytochrome P450 spectral changes as well as alterations in the n-heptane metabolic profile. The observed modifications in the biotransformation of n-heptane indicated that there are three distinct pathways for oxidation of n-heptane to heptanols, heptanones, and one-side oxygen-oriented heptanediones.