Immobilization Of Papain And The Study Of Its Kinetic Properties

Immobilized enzyme is a new scientific field which has been quickly developed since 1970s. It not only broke the traditionally idea but also brought strong drive to industry revolution. The aim of this study was to immobilized papain by two different methods. With casein as substrate, we have studied the effect of the immobilization conditions on the relative activity and some properties of both the free and the immobilized enzyme.First, Papain was immobilized on silica gel by y-glycidoxypropyl- trimethoxysilane. The optimum immobilization conditions of the enzyme were as follows: the temperature was 25 , pH was 8.0, time was 18h, and the amount of enzyme was 24mg per 100mg 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 of the immobilized enzyme were a little higher than the free one, and the thermal stability of the immobilized enzyme was better than that of the free. Meanwhile, the effects of some salts and organic solvents on the free and immobilized enzyme were also discussed.Immobilization of enzyme via diazonium ions is an important method. Traditionally, when immobilization of enzyme on inorganic carrier by this method, hazardous p-nitrobenzoyl chloride has to be used in the preparation of aromatic compounds and this compound has to be reduced to aromatic amine. The present work is to develop an alternative method of amidation. We have aminated p-aminobenzoic acid by aminated silica gel to produce a new carrier. By immobilizing papain on this new carrier, the immobilization conditions and some properties of both the free and the immobilized enzyme have been studied. The optimum immobilization conditions of the enzyme were as follows: pH was 7.0, time was 6h, and the amount of enzyme was 288mg per g silica gel. The results showed that the optimum pH and temperature of the immobilized enzyme were a little higher than the free one, and the thermal stability of the immobilized enzyme was better than that of the free one.