Kinetic analysis of compound I formation and the catalatic activity of chloroperoxidase

Abstract

When the only substrate added to a solution of chloroperoxidase is a hydroperoxide, the reactions are: ferric enzyme + ROOH leads to compound I + ROH and compound I + ROOH leads to ferric enzyme + O2 + ROH. When H2O2 is used as substrate, the rate constants for the formation and catalatic decomposition of compound I are 2.4 X 10(6) M--1.S--1 and 3.4 X 10(5) M--1.S--1 at pH 4.7 and it is predicted that a maximum of 87% of the enzyme converts to compound I in the steady state of the catalatic reaction. With methyl hydroperoxide, formation of compound I has a rate constant of 4.7 X 10(5) M--1.S--1 and its decomposition 2.9 X 10(4) M--1.S--1. When peracetic acid is used, compound I is formed with a rate constant of 3.8 X 10(6) M--1.S--1 and a 100% yield of compound I is obtained.