Kinetics of two-electron oxidations by the compound I derivative of chloroperoxidase, a model for cytochrome P450 oxidants

[structure: see text] Rate constants for two-electron oxidation reactions of Compound I from chloroperoxidase (CPO) with a variety of substrates were measured by stopped-flow kinetic techniques. The thiolate ligand of CPO Compound I activates the iron-oxo species with the result that oxidation reactions are 2 to 3 orders of magnitude faster than oxidations by model iron(IV)-oxo porphyrin radical cations containing weaker binding counterions.