Kinetic study of hydrogen peroxide decomposition by catalase in a flow-mix microcalorimetric system

The kinetics of hydrogen peroxide decomposition by the enzyme catalase was studied at pH 7.4 in the temperature range 10–30 °C. Experiments were performed by the LKB-2277 Thermal Activity Monitor equipped with a flow-mix cylinder. The calorimetric reaction unit was schematised as a tubular reactor operating under plug-flow conditions. A first-order kinetic expression, with respect to both the substrate and the enzyme, was used to describe the rate of hydrogen peroxide decomposition. Regression analysis of calorimetric data provided a molar reaction enthalpy of −87.55 kJ mol−1 and an activation energy of 11 kJ mol−1. Analysis of model residuals and the normal probability plot indicated that the results obtained were statistically significant.