Kinetics of the reaction of compound II of horseradish peroxidase with hydrogen peroxide to form compound III

• DOI: 10.1111/j.1432-1033.1989.tb15246.x
• Publication Date: 2005-03-04T03:55:06Z
• Authors: Suara A. ADEDIRAN; Anne‐Marie LAMBEIR
• Keywords: Horseradish peroxidase; Reaction rate; Flash photolysis

The kinetics of the reaction H2O2 with compound II horseradish peroxidase were studied as a function pH at 25 degrees C and constant ionic strength 0.11 M. involves transient formation ferric superoxide anion first step followed by intermediate species to form III. Both reactions are also observed peracetic acid substrate, though amplitude was too small for rate be measured. Observation not possible below 8.5 under conditions this investigation. It tends occur faster lower so an increasing fraction is lost in dead time stopped-flow apparatus. constants second reaction, leading III formation, all values, maximum 20 M-1 s-1 7.0. Groups on enzyme pKa values 4.2 9.1 appear involved reaction. Compound accompanied oxidation aromatic amino groups protein. formed from hydrogen peroxide has bands molar absorption coefficients excellent agreement those obtained flash photolysis aerated carbonmonoxyperoxidase [Wittenberg, J. B., Noble, R. W., Wittenberg, B. A., Antonini, E., Brunori, Wyman, (1967) Biol. Chem. 242, 626-634]. Attempts use m-chloroperbenzoic oxidant resulted destruction II.