α-环状糊精葡萄糖基转移酶的固定化及其性质研究

研究了一种α-环糊精葡萄糖基转移酶的固定化和固定化酶的性质。通过对戊二醛浓度、酶量和交联时间各单因素的考察，确定了最佳的固定化条件。与游离酶相比，以DEAE纤维素为载体的固定化酶最适pH向酸性偏移，最适温度不变，pH稳定性和热稳定性都有所提高。在40℃、150r/min下反应3h，转化率可以达到32%。固定化酶可以连续使用4次以上。固定化酶在4℃、5mmol/L CaCl2溶液里保存18d，还剩余80%以上的活力。

Immobilization of an а-Cyclodextrin Glucanotransferase from Bacillus sp.602-1 and its Characterization

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.