酪蛋白水解物的酶法修饰与ACE抑制活性变化

利用枯草杆菌碱性蛋白酶水解酪蛋白制备酪蛋白水解物,其水解度为11.2%,IC50为47.1μg/mL。再应用相同的酶对酪蛋白水解物进行类蛋白反应修饰,考察底物浓度、温度和酶添加量对类蛋白反应的影响,并制备5个不同的修饰产物测定其ACE抑制活性和IC50值。结果表明,修饰产物的ACE抑制活性随修饰程度(游离氨基减少量)的增加而提高,并且都高于未经修饰的酪蛋白水解物。当游离氨基减少量为154.65μmol/g(蛋白)时,修饰产物的IC50值可降至0.6μg/mL。毛细管电泳分析结果显示类蛋白修饰后水解物的多肽组成情况发生明显变化。研究结果证明酪蛋白水解物的ACE抑制活性可以通过类蛋白反应的修饰作用而提高。

Enzymatic Modification of Casein Hydrolysates and Improvement in ACE Inhibitory Activity

Casein hydrolysates that had the degree of hydrolysis of 11.2% and value of IC 50 about 38.6 μg/mL were prepared from casein with Bacillus subtilis alkaline protease.Casein hysrolysates then were modified by plastein reaction with the same protease.The effects of the concentration of casein hydrolysates,temperature and addition level of protease on the plastein reaction were studied.Five modified casein hydrolysates with different modification extents were prepared and their ACE inhibitory activity and value of IC 50 were determined.The results indicated that all five modified casein hydrolysates had higher ACE inhibitory activity than that of casein hydrolysates.When modified casein hydrolysates had a decrease in free amino groups of 154.65 μmol/g protein,their ACE inhibitory activity was decrease to 0.6 μg/mL.Analysis results from capillary electrophoresis indicated that the peptide profiles between casein hydrolysates and modified casein hydrolysates were different obviously.The study results showed that the ACE inhibitory activity of casein hydrolysates could be effectively improved by plastein reaction.