[Heat inactivation of cytochrome P-450]

Thermal inactivation of cytochrome P-450 in different states (microsomes, highly purified and immobilized), characterized by the loss of catalytic activity in cumene hydroperoxide--dependent aniline hydroxylation has been studied in the temperature range 40-58 degrees C. The process of thermoinactivation is characterized by the first order rate constants. From the temperature dependence of these constants the energy of activation and the activation parameters of cytochrome P-450 thermoinactivation have been determined at 45 degrees C. In the presence of 20% glycerol the activation parameters of cytochrome P-450 thermoinactivation in microsomes in highly purified and immobilized states are very similar.