Biological activity of urokinase immobilized to cross-linked poly(2-hydroxyethyl methacrylate)

The fibrinolytic enzyme urokinase was immobilized by encapsulation or cross-linking to poly(2-hydroxyethyl methacrylate) networks. The immobilized urokinase was more thermally stable, more stable against pH change and more resistant to inactivation by plasma protease inhibitors. These stabilities were improved with increasing degree of cross-linking. On the other hand, the enzymatic activity of immobilized urokinase decreased with increasing degree of cross-linking. A suitable degree of cross-linking is needed for the maintenance of high biological activity of immobilized urokinase over a long period.