采用稳定剂提高右旋糖酐酶热稳定性

Enhancing dextranase thermal stability by stabilizers

向右旋糖酐酶中添加金属离子、糖类、多元醇类以及表面活性剂等物质,利用单因素试验,选择三类物质中各自对其热稳定性提升效果最优的三种单稳定剂后,对单稳定剂进行浓度梯度优化,并根据结果设计三因素三水平正交试验,确定一种复合稳定剂配方。利用DNS法测定添加稳定剂前后及高温保温前后的右旋糖酐酶酶活,计算酶活保留率,分析右旋糖酐酶的热稳定性能及复合稳定剂的效果。结果表明,Na^(+)、甘露醇和Tween 80三种稳定剂能显著提高右旋糖酐酶热稳定性,通过正交试验得到优化的复合稳定剂配方,即Na^(+) 100mmol·L^(-1)、甘露醇125g·L^(-1)和Tween 803g·L^(-1)。在50℃下,添加复合稳定剂的右旋糖酐酶保温1h后,酶活保留率和半衰期分别为85.89%和4.56h,较对照组分别提高43.95%点和4.7倍。

Metal ions,sugars,polyols and surfactants three protective agents were added into dextranase,single factor test was used to choose the best single enhancer that could increase dextranase thermal.The concentration optimization of each single protective agents were carried out.The optimal combination formula was determined by three factors and three levels orthogonal design experiments.Enzyme retention rate was calculated by determining dextranase enzyme activity before and after adding combined stabilizer and before and after keeping higher temperature.Dextranase enzyme stability under heat and combined stabilizers’effects were analyzed.The results indicated that Na^(+),mannitol and Tween 80 could significantly improved the thermal stability of dextranase.The optimal combination(Na^(+) 100mmol·L^(-1),mannitol 125g·L^(-1) and Tween 803g·L^(-1))was obtained using orthogonal experimental design.The residual activity of dextranase with combined stabilizers and half-life were 85.89%and 4.56h,respectively,increased by 43.95%and 4.7 times compared with the control group which was kept at 50℃for 1h.