IMMOBILIZATION OF ENZYMES IN PHOTOCHEMICALLY CROSS-LINKED POLYVINYL-ALCOHOL

Invertase and amyloglucosidase were entrapped in polyvinyl alcohol mem branes through UV irradiation of pendent styrylpyridinium groups. The influence of cross-linking on immobilization efficiency was studied us ing prepolymers with varied cross-linker density, the above mentioned enzymes of different molecular weight, and various substrates. It was found that the larger enzyme invertase is effectively immobilized even in polymers with very low contents of the cross-linking component. In contrast for an effective immobilization of amyloglucosidase, a highe r degree of cross-linking is necessary. Although there is only a sligh t loss in amyloglucosidase activity the apparent activity, especially for the macromolecular substrate starch, is low. This is contributed t o a hindered diffusion of the substrates in the swollen hydrogel matri x. The influence of the diffusion is also reflected in the kinetic par ameters K-m and V-max The pH and temperature optima of entrapped amylo glucosidase are similar to those of the native enzyme in solution.