title: Structure of horseradish peroxidase compound I. Kinetic evidence for the incorporation of one oxygen atom from the oxidizing substrate into the enzyme.
abstract: The kinetics of the reaction between horseradish peroxidase and p-nitroperbenzoic acid to form compound I have been studied at 25 degrees C in phosphate buffer pH 7.2 and ionic strength of 0.11 M by transient-state and steady-state methods. The second-order rate constant for compound I formation obtained by stopped-flow measurements at 403 nm is (3.7 +/- 0.2) x 10(7) 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) x 10(7) M-1 s-1. The results provide an independent confirmation that one and only one oxygen atom is incorporated from the oxidizing substrate into compound I.
mesh_terms: D002264:Carboxylic Acids / Q000378:metabolism; D055598:Chemical Phenomena; D002621:Chemistry; D006735:Horseradish Peroxidase / Q000378:metabolism*; D007700:Kinetics; D010084:Oxidation-Reduction; D010100:Oxygen; D010544:Peroxidases / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D002264:Carboxylic Acids; D006735:Horseradish Peroxidase; D010544:Peroxidases; D010100:Oxygen