保护剂提高β-甘露聚糖酶热稳定性的研究

Enhancing the Thermostability of β-Mannanase by Protective Additives

研究了几种糖类(葡萄糖、甘露糖、果糖、蔗糖和壳聚糖)和多元醇类(乙醇、丙三醇和山梨醇)保护剂提高β-甘露聚糖酶热稳定性的作用,并考察了在特定保护剂存在时该酶的最适反应温度和失活热力学以及动力学.实验表明,蔗糖、壳聚糖和山梨醇在浓度均为2 g/L时能够显著提高该酶的热稳定性;通过正交实验得到了一种效果最佳的复合保护剂(蔗糖、壳聚糖、山梨醇之比为1∶2∶2);蔗糖、壳聚糖、甘油、山梨醇和复合保护剂的添加均能使β-甘露聚糖酶的最适反应温度从原来的50℃提高到60℃左右;65℃下β-甘露聚糖酶的热失活曲线遵循一级反应规律,计算得到了不同保护剂下酶失活的动力学和热力学参数值,并分析了保护剂提高β-甘露聚糖酶热稳定性的机理.

The effects of sugars （glucose, mannose, fructose, sucrose and chitosan） and polyols （glycol, glycerol and sorbitol） on the thermostability of β-mannanase were studied, and the optimal reaction temperatures of β-mannanase as well as thermodynamics and kinetics of inactivation with and without additives were discussed. Three additives （sucrose, chitosan and sorbitol） showed good performance to improve the activity of β-mannanase when their concentrations were kept at 2 g/L. The optimal combination additive （sucrose： chitosan： sorbitol is 1：2：2） was obtained using the orthogonal experimental design. These additives （sucrose, chitosan, glycerol, sorbitol and combination additive） may increase the optimal reaction temperature from 50 ℃ to about 60 ℃ due to their good protection effect. The thermal inactivation curves of β-mannanase accorded with the rules of the first order reaction at 65 ℃ and corresponding kinetic and thermodynamic parameters were calculated. Meanwhile, the protective mechanism of stabilizing additives against inactivation of enzyme was also discussed.