纳豆芽孢杆菌蛋白酶的制备及性质研究

Preparation and Characterization of Protease from Bacillus natto

纳豆芽孢杆菌是纳豆发酵生产的主要菌种,对其胞外蛋白酶催化特性的研究有助于了解纳豆的发酵生产过程,并有利于从中发掘有开发应用潜力的蛋白酶。实验从不同纳豆产品中分离筛选得到1株高产蛋白酶的纳豆芽孢杆菌,对其胞外蛋白酶的催化特性及活性影响因子进行了分析。结果显示,纳豆芽孢杆菌蛋白酶是一典型的金属蛋白酶,EDTA几乎可完全抑制其活性,Ca2+是其活性中心的辅基;该蛋白酶在60℃、pH 7.0有最大催化活性,在pH 6～9和低于45℃条件下具有很好的稳定性;50℃时,该蛋白酶会缓慢失活,其热失活规律符合一级指数衰减模型:a=0.124+0.887e(-0.45t);该蛋白酶对大豆蛋白有很强的水解能力,其水解效率与Alcalase蛋白酶相当,可以实现底物蛋白的深度水解,具有一定的开发应用价值。

Bacillus natto was the primary microorganism used in the production of natto, and the study on the characterization of protease from Bacillus natto will help to conduct the production of natto and to explore new protease. One Bacillus natto of high-yield protease was isolated from natto, and catalysis characterization of protease secreted from this Bacillus natto was investigated. Results indicated： protease from Bacillus natto was a particular Metalloproteases, it could be completely inhibited by EDTA,and had Ca2~ in the active center. The protease had the maximum activity at pH 7.0 and 60℃ and was stable in the pH range of 6.0 - 9.0 and below 45℃. The protease was unstable at 50℃ and the kinetics of deactivation fit the model： a = 0. 124 ＋ 0. 887e^（ -0.45t）. Protease from Bacillus natto has a very high hydrolysis efficiency to soy protein, meaning that it＇s a good application in the production of hydrolysate of food protein.