Poly-lysine supported cross-linked enzyme aggregates with efficient enzymatic activity and high operational stability

In this study, the operational stability of enzymes in a cross-linked aggregate (CLEA) formed with poly-lysine was examined. Chymotrypsin, subtilisin, citrate synthase and laccase, which are structurally and mechanistically diverse, were used as model enzymes. The preparation of poly-lysine supported CLEA was completed within 3 h. The immobilized enzymes were more stable than free enzymes at high temperature, in the presence of a chemical denaturant or in an organic solvent and were recycled without appreciable loss of activity. In addition, the immobilized proteases showed higher or similar hydrolytic activity in acidic pH than in neutral pH. This immobilization method was also applicable to the multi-subunit protein. These results suggest that the poly-Lys supported CLEA can be used as catalysts with own enzymatic activity and high operational stability.