Regioselectivity and Activity of Cytochrome P450 BM-3 and Mutant F87A in Reactions Driven by Hydrogen Peroxide

Cytochrome P450 BM-3 (EC 1.14.14.1) is a monooxygenase that utilizes NADPH and dioxygen to hydroxylate fatty acids at subterminal positions. The enzyme is also capable of functioning as a peroxygenase in the same reaction, by utilizing hydrogen peroxide in place of the reductase domain, cofactor and oxygen. As a starting point for developing a practically useful hydroxylation biocatalyst, we compare the activity and regioselectivity of wild-type P450 BM-3 and its F87A mutant on various fatty acids. Neither enzyme catalyzes terminal hydroxylation under any of the conditions studied. While significantly enhancing peroxygenase activity, the F87A mutation also shifts hydroxylation further away from the terminal position. The H2O2driven reactions with either the full-length BM-3 enzyme or the heme domain are slow, but yield product distributions very similar to those generated when using NADPH and O2.