Immobilization of cellulase on a reversibly soluble-insoluble support: properties and application.

Cellulase was coupled to N-succinyl-chitosan (NSC) showing soluble-insoluble characteristics with pH change. Cellulase immobilized on NSC (NSCC) is in a soluble state during the enzyme reaction, yet can be recovered in its insoluble form by lowering the pH of the reaction solution after the reaction. NSCC was obtained under the optimized immobilization conditions of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) 10 mg, cellulase 15 mg, and pH 5.0. The retention activity of the immobilized cellulase was found to be 48.8%. The effects of pH and temperature on the activity and stability of NSCC were studied and compared with those of free cellulase. The optimum temperature and pH of NSCC was 45 degrees C and 4.0, respectively, which was found unchanged compared with the free one. The stability of cellulase against change in the pH and temperature was improved by the immobilization. The effectiveness of employing NSCC for extracting flavonoids from Ginkgo biloba leaf powder was investigated. Results showed that NSCC enhanced extraction yield up to 2.35-fold when compared with the conventional method. Moreover, NSCC retained 83.5% of its initial activity after five batches of hydrolysis reaction.