A hydrogen peroxide assay based on the peroxidase-oxidase reaction. Numerical simulation of the reaction mechanism

In order to explain an assay method for H2O2, based on the horseradish peroxidase/NADH/H2O2 system, we performed a numerical simulation of this complex reaction mechanism. For this purpose, we applied a simplified version of a model designed by Yokota and Yamazaki to our experimental conditions [Yokota, K. & Yamazaki, I. (1977) Biochemistry 16, 1913-1918]. This modification leads to a kinetic behaviour of the system very similar to our experimental results when the presence of superoxide dismutase is simulated. These simulations confirm that hydrogen peroxide concentrations are proportional to the total amount of NADH oxidized. We also showed that superoxide dismutase activity can be determined by this assay method. Moreover, in samples containing superoxide dismutase and hydrogen peroxide, the simulations showed that both superoxide dismutase and hydrogen peroxide can be determined using our assay method.