CROSS-LINKING TECHNIQUES - APPLICATIONS TO ENZYME AND PROTEIN STABILIZATION AND BIOCONJUGATE PREPARATION

Chemical crosslinking technology was used for (a) enhancing the stability of trypsin, beta-galactosidase, and concanavalin A and (b) forming protein-protein conjugates viz. trypsin-chymotrypsin, trypsin-beta-galactosidase, and concanavalin A-beta-galactosidase. For stabilization of the three proteins, dimethyl adipimidate was found to give the best results. The intramolecularly crosslinked trypsin, with an average of 9.5 groups modified out of 14 free amino groups present, showed a much slower rate of autolysis at 40-degrees-C compared to native trypsin. Crosslinked beta-galactosidase entrapped in polyacrylamide hydrolyzed 47% of milk lactose in 6 h and at 55-degrees-C. Entrapped native enzyme hydrolyzed only 31% substrate under the same conditions. Besides preparing an insoluble aggregate of trypsin-chymotrypsin and beta-galactosidase, conjugates of trypsin-chymotrypsin, trypsin-alkaline phosphatase, and Concanavalin A-beta-galactosidase were also prepared and evaluated.