Synthesis of macroporous polymer carrier and immobilization of papain

Amacroporous resin microbeads of methyl methacrylate-divinyl benzene copolymer synthesized by radical suspension polymerization with divinylbenzene in the presence of a pore-creating agent, petroleum ether. They have big specific surface area and a large degree of porosity was covered on all surface of the resin. This macroporous polymer carrier was aminated by hydrazine hydrate, to produce a large number of amino groups onto the carrier. Papain was immobilized on the porous polymer carrier by a glutaraldehyde cross-linking method or a diazo-coupling method. The determining factors involved with the activity recovery of the immobilized papain and the enzymic properties of the resulting immobilized papain were studied in comparison with free papain, for which casein was chosen as a substrate. The results show that the activity recovery of immobilized papain can reach 60.1%. At the same time, the stability, resistance against inhibition, the Michaelis constant Km, and reusability of the immobilized enzyme were also investigated. The results indicated that the immobilized papain by this percentage reached had not only higher activity recovery, but also is had remarkable stability, better reusability and environmental adaptability than free papain.