Immobilization of urokinase on agarose matrices

Immobilization of urokinase, a plasminogen activator, was carried out to determine the effect of spacer length used on the immobilized enzyme activity. The enzyme was covalently coupled to agarose gel, both directly to the matrix and also via interposing different lengths of spacer groups. The specific activity of immobilized urokinase increased as the spacer length (n') increased to a certain length and tended to decrease thereafter. The maximal activity was shown when the value of n' was 7 for the agarose-NH-(CH2)n-CO-NH-(CH2)2-CO-NH-urokinase series. The coupling yield of the enzyme activity was from 33 to 68% depending on various forms of immobilized urokinase. The immobilized urokinase was characterized with regard to pH, temperature, storage, and thermal stabilities.