PREPARATION AND PROPERTIES OF REVERSIBLY SOLUBLE-INSOLUBLE IMMOBILIZED CELLULASE ON EUDRAGIT L-100

摘要

pH-responsive immobilized cellulase was prepared by noncovalent and covalent methods. Covalently immobilized celluase with carbodiimide showed more excellence on both immobilization efficiency and reusability than noncovalently immobilized cellulase by adsorbility. NHS (N-hydroxysuccinimide could be used to improve efficiency of covalent coupling that the retained activity of the immobilized cellulase could improve 13.76% (with and without of the enhancer was 84.21% and 70.45%, respectively.).The immobilized cellulase had broader optimum temperature between 55 and 60°C than free cellulase (the optimum temperature was 55°C). The optimum pH values of free and immobilized ceilulase were 4.75, 5.25, respectively. Immobilized cellulase could retain higher activity than free cellulase above pH 5.0. The Km value of the immobilized cellulase and free celluase was 85.55 and 73.84 g·L-1 respectively. The Vmax of immobilized cellulase showed a slight decrease from 2.49 (for free cellulase) to 2.34 μmol'ml-1·min-1. There was about 50% of remained productivity after 5 cycles for hydrolysis of both microcrystal cellulose and alkali-pretreated straw.