Grafting of polyacrylamide onto silica gel and its application to enzyme immobilization

Polymerization of acrylamide was carried out in a redox system consisting of ceric iron and mercapto groups introduced onto silica gel. In the course of the polymerization, plyacrylamid was grafted onto the surface of the silica gel. The amount of the grafted polymer reached 130 mg per gram of the silica gel employed in the polymerzation. In order to immobilize glucose oxidase on the silica gel, the coupling reaction between the grafted polymer and the enzyme was attempted in the presence of a condensing agent. It was shown that 4.3 mg of the enzyme was immobilized on 1 g of the polyacrylamid-grafted silica gel, and the enzyme immobilized product had an apparent activity of 50 units/g. The pH-activity and temperature-activity profiles of the immobilized enzyme resembled those of the native enzyme. A kinetic study of the glucose oxidation with the immobilized enzyme allowed the consideration that the enzyme immobilization caused retardation of lactone formation from the enzyme-glucose complex. The immobilized enzyme kept 95% of its original activity in water over a period of 3 months.departmental bulletin pape