In situ entrapment of α-chymotrypsin in the network of acrylamide and 2-hydroxyethyl methacrylate copolymers

A mild and reproducible method has been developed for the entrapment of α-chymotrypsin into a crosslinked copolymer. A porous copolymer was synthesized at 293 K by solution copolymerization of acrylamide and 2-hydroxyethyl methacrylate. α-Chymotrypsin was entrapped during copolymerization at different polymerization stages. The effect of crosslinking on enzyme loading and retention of its activity was examined. Copolymer with 2% crosslinking could entrap >90% of the enzyme. The activity of free and immobilized α-chymotrypsin was determined by using N-benzoyl-L-tyrosine ethyl ester and casein as low and high molecular weight substrates respectively. Storage as well as thermal stability of the immobilized enzyme was superior to that of the free one. Effect of calcium and heavy metal ions was studied on immobilized enzyme activity. The immobilized enzyme showed little variation in activity with pH and retained 50% activity after nine cycles. The Michaelis constant Km of the free and immobilized enzyme was estimated to be 2.7 and 4.2 × 10-3 mM, respectively, indicating no conformational changes during entrapment.