Study of the Immobilization of Papain on Epoxide-Activated Silica and Kinetic Properties of Immobilized Enzyme

Papain was immobilized on silica gel by γ-glycidoxypropyltrimethoxysilane. The optimum immobilization conditions of the enzyme were as follows: the temperature was 25 ℃, pH was 8.0,time was 18 h, and the amount of enzyme was 24 mg per 100 mg epoxide-activated silica. Some kinetic properties of the free and the immobilized enzyme were studied with casein as substrate. The results showed that the optimum pH and temperature for the immobilized enzyme were slight higher than those for the free one, and the thermal stability of the immobilized enzyme was better than that of the free. Meanwhile, the effect of some salts and organic solvents on the free and immobilized enzyme was also discussed.