TRYPSIN MODIFICATION BY VINYL-POLYMERS WITH VARIABLE SOLUBILITIES IN RESPONSE TO EXTERNAL SIGNALS

Trypsin was modified with various vinyl polymers by the graft polymerization of vinyl monomers using a trypsin derivative containing aliphatic azo groups as the initiator. The graft polymers were chosen to be sensitive to external signals, e.g., a redox-sensitive poly[3-carbamoyl-1-(p-vinylbenzyl)pyridinium chloride] and a pH-sensitive poly(methacrylic acid-co-methyl methacrylate). The trypsin modified with the redox-sensitive polymer became insoluble in water in the presence of Na2S2O4, and redissolved when H2O2 was added. However, the enzymatic activity of the homogeneous solution was not proportional to the concentration of the modified trypsin remaining in the solution. The trypsin modified with the pH-sensitive polymer was insoluble and soluble in acidic and neutral solutions, respectively. The enzymatic activity of the homogeneous solution changed reversibly with pH in proportion to the concentration of the modified trypsin remaining in the solution.