本实验采用芽孢杆菌丝氨酸蛋白酶及其突变产物对淡水鱼类白鲢鱼肉蛋白进行酶解，对比分析了酶的不同突变产物对水解过程水解度的影响及其酶解产物的抗氧化活性变化。大部分蛋白酶在水解反应前40 min内反应速率较高，水解度迅速增加，40 min~120 min之间水解曲线变得平缓甚至下降。其中细菌丝氨酸蛋白酶突变子239对白鲢鱼肉蛋白的水解能力最强，其2 h水解产物水解度最大，为11.51%；突变蛋白酶33的水解能力最差，最终水解产物的水解度只有3.08%。细菌丝氨酸蛋白酶及其突变酶的酶解产物均具有较高的抗氧化性，其中蛋白酶突变子166的酶解产物抗氧化活性最强，经测定其DPPH清除能力为91.02%，蛋白酶突变子169的酶解产物抗氧化活性最弱，DPPH 清除能力为61.41%。结果表明，与三联体催化活性中心相关的突变对丝氨酸蛋白酶的水解能力和水产品蛋白的水解度影响较大，而酶底物特异性方面的改变则影响酶解产物的抗氧化活性。

In this study, hydrolysis ability of bacterial serine protease and its mutants on silver carp protein was analyzed and antioxidant activities of protein hydrolysates were evaluated. Majority of the proteases in the hydrolysis reaction within the first 40 min was severe and the degree of hydrolysis increased rapidly. Then hydrolysis curves become flat or even decline from 40 min to 120 min. Bacterial serine protease mutant 239 showed the strongest hydrolysis ability on silver carp fish protein, which the maximum hydrolysis degree was 11.51% after 2 hours, whereas mutant 33 showed less degree of hydrolysis with only final 3.08%. The results showed that the bacterial serine protease and its mutant enzymes have high antioxidant activity. Protein hydrolysates of silver carp protein from mutant 166 have a strongest antioxidant activity by the DPPH scavenging was 91.02% with weak 61.41% DPPH scavenging ability for protease mutant 169. The resulted indicated that mutant in the domain related to active center will change the hydrolysis ability of protease. The mutant in substrate specificity domains will affect antioxidant activity of protein hydrolysates.

国家自然科学基金项目（30800735）；福建省自然科学基金项目（2009J06014）