The Kinetics of Oxidation of 3-Aminopyridin-2(1H)-ones by Hydrogen Peroxide in the Presence of Horseradish Peroxidase

Abstract

The aim of this study was to evaluate the kinetic parameters of the oxidation of some 3-aminopyridine-2(1H)-ones by hydrogen peroxide catalyzed by horseradish peroxidase and the affinity of horseradish peroxidase to these compounds. It has been shown that the oxidation of 3-aminopyridine-2(1H)-ones follows kinetics of the pseudo-first order. A hyperbolic decrease in the observed reaction rate constant (k_obs) was also found with an increase in the initial concentration of 3-aminopyridine-2(1H)-ones. The dependence of k_obs on the concentration of the enzyme was linear, suggesting competitive inhibition of oxidation by the reaction product. It was found that an increase in the polarity of the substituent in the fourth position leads to an increase in the rate of oxidation of pyridinones. V_max/K_m values were also higher for compounds carrying polar substituents in the fourth position. This kinetic parameter (V_max/K_m) reflects the substrate specificity of the enzyme. The data we obtained clarify the mechanisms of interaction between horseradish peroxidase and 3-aminopyridinones and suggest that 3-aminopyridinones can be used to develop sensitive methods for the detection of hydrogen peroxide and modification of immune enzyme analysis techniques.