Inactivation kinetics of enzyme pharmaceuticals in aqueous solution

The kinetics of enzyme inactivation in aqueous solution of neutral pH were studied for alpha-chymotrypsin, bromelain, and kallikrein. Inactivation of alpha-chymotrypsin and bromelain followed simple first-order kinetics, and the rate constant obtained conformed to the Arrhenius relationship. Kallikrein, however, presented more complicated kinetics of inactivation, which could be described by a kinetic expression combining a reversible and an irreversible pathway. Nonlinear regression analysis suggested that the rate constants conform reasonably well to the Arrhenius relationship. The results suggest that inactivation of enzymes in aqueous solution can be modeled even if the profile is complicated and that the inactivation rates can be predicted based on the relationship between the parameter estimates and temperature.