Structure of Horseradish Perosidase Compound I

Abstract
The kinetics of the reaction between horseradish peroxidase and p-nitroperbenzoic acid to form compound I were studied at 25.degree. C in phosphate buffer pH 7.2 and ionic strength of 0.11 M by transient-state and steady-state methods. The 2nd-order rate constant for compound I formation obtained by stopped-flow measurements at 403 nm is (3.7 .+-. 0.2) .times. 107 M-1 s-1. For the disappearance of p-nitroperbenzoic acid and appearance of p-nitrobenzoic acid using steady-state kinetics measured at 265 nm the rate constant is (3.0 .+-. 0.6) .times. 107 M-1 s-1. The results provide an independent confirmation that one, and only 1, oxygen atom is incorporated from the oxidizing substrate into compound I.