HYDROLYSIS OF STARCHY MATERIALS BY REPEATED USE OF AN AMYLASE IMMOBILIZED ON A NOVEL THERMORESPONSIVE POLYMER

A copolymer of methacrylic acid (MAA) and N-isopropyl acrylamide (NIPA M) was used as a novel, reversibly soluble-insoluble support whose sol ubility changes depending on the temperature of the solution. Amylase (Dabiase K-27) immobilized covalently on the thermo-responsive polymer showed good solubility response: the immobilized enzyme (D-MN) was in a soluble state below 32 degrees C, but insoluble above 42 degrees C. D-MN in a soluble state has a high specific activity for the hydrolys is of soluble or uncooked starch. The solubility response of D-NM to c hanges in the temperature of the solution was more sensitive when 0.5% NaCl was added to a buffer solution (pH 4.5) with D-MN than in the bu ffer solution without NaCl D-MN was used successively for repeated hyd rolysis reactions of soluble and uncooked starches, in which D-MN was insolubilized either by changing the temperature of the reaction mixtu re from 30 degrees C to 36 degrees C with 0.5% NaCl or by adjusting th e NaCl concentration of the reaction mixture from O% to 1% at 30 degre es C. In the repeated hydrolysis, glucose was produced successively fr om the soluble and uncooked starches, and D-MN could be repeatedly use d after being recovered from the reaction product by centrifugation at the end of each batchwise hydrolysis.