中国生物工程杂志

Abstract An α-Cyclodextrin glucanotransferase(CGTase) from Bacillus sp.602-1 was immobilized on DEAE cellulose by covalently binding with glutaraldehyde. Key parameters for immobilization, such as concentration of glutaraldehyde, amount of enzyme and immobilization time, were optimized respectively. Properties of the immobilized CGTase were further investigated. No difference was observed on the optimal temperature between free enzyme and immobilized one, but the optimal pH of the latter shift from 6 to 5. pH and thermal stability of the immobilized CGTase increased to some extent. The yield of cyclodextrin reached 32% after conversion by the immobilized CGTase on starch at 40℃ for 3h, 150r/min. The immobilized CGTase could be used for 4 cycles continously. After being stored for 18 days at 4℃ in 5mmol/L CaCl2 solution, residual activity of the immobilized CGTase remained 80%.This work will be helpful for the industrial application of the α-cyclodextrin.