Kinetics of Thermal Inactivation of Chicken Pepsin

Thermal inactivation of chicken pepsin was studied at pH 3, 4, and 6. Application of heat to enzyme solutions in capillary tubes enabled attainment of short come-up times. Enzyme denaturation followed first order reaction kinetics, exhibiting reasonably high thermal resistance. Activation energies of denaturation were 25.6, 28.0, and 30.0 kcal/mole for pH 6, 4, and 3, respectively. These are considerably lower than corresponding activation energies for other commonly utilized milk clotting enzymes. Thermal resistance and low activation energy of denaturation of chicken pepsin calls for care to inactivate properly the residual enzyme of whey products where its proteolytic activity may be undesirable.