Properties of Immobilized Papain on Thermally Sensitive Carrier and Its Application for HCG Antibody Digestion

Traditional solid phase immobilized enzyme shows low catalytic efficiency,especially when acting on macromolecular substrate.Here the thermally sensitive material poly(N-isopropylacrylamide),which was esterified by N-hydroxysuccinimide,was employed as a carrier for the immobilization of papain,and some properties of the immobilized papain were investigated.From the study it was found that the optimal pH value and temperature for immobilized papain activity were 7.5 and 65 ℃ respectively,and the Michaelis constant was 2.72 mg/mL.The immobilized papain left was 86.6% of the activity after 24 thermal cycles.After stored at 4 ℃ for 60 d,the immobilized papain activity retained 71.5%.Compared with free enzyme,the pH value,thermal,operational and storage stabilities of immobilized papain were obviously improved.The immobilized papain was applied to the digestion of HCG monoclonal antibody.Compared with the papain immobilized on cellulose,the hydrolysis capacity of the thermally sensitive immobilized papain was higher and the operation was more convenient.It was more suitable for the enzymatic hydrolysis of the macromolecules,especially the preparation of antibody fragments.