Coimmobilization of glucoamylase and glucose isomerase by molecular deposition technique for one-step conversion of dextrin to fructose

Glucose isomerase was immobilized by itself with adsorption and coimmobiliz ed with glucoamylase by molecular deposition technique using macroporous tr imethylamine polystyrene beads. Approximately 77.5% of the enzyme added was immobilized. The pH-activity curve of the immobilized glucose isomerase wa s broadened, resulting in 75% retention of its maximum activity at pH 6.2. The K-m of the immobilized glucose isomerase was 1.28-fold that of the solu ble one. When the two enzymes were immobilized together, the system was fou nd capable of functioning at pH 6.0 to produce fructose from starch and dex trin. At this pH, the total fructose output of the coimmobilized enzyme sys tem after 24 h was 1.9 times that of the free enzyme system. (C) 1999 Elsev ier Science B.V. All rights reserved.