Introduction of P450, peroxidase, and catalase activities into myoglobin by site-directed mutagenesis: Diverse reactivities of compound I

We have prepared several myoglobin (Mb) mutants which are protein models for peroxidase, P450, and catalase. In most cases, the distal site of Mb was modified by site-directed mutagenesis on the basis of mechanisms of peroxidase, P450, and catalase reactions. The most important feature of the Mb mutants is the direct observation of their active intermediates, so called compound I. Under catalytic oxidations of sulfides and styrene by H2O2, up to 97% of enantioselectivity was observed. Introduction of an aromatic substrate, tryptophan, near the heme by the site directed mutagenesis of Mb allowed us to proceed almost stoichiometric aromatic hydroxylation. In addition, compound I of Mb mutants exhibit the catalase activity. These results demonstrate that the compound I of Mb mutants are capable to proceed all of the peroxidase, P450, and catalase reactions.