Casein was hydrolyzed by Alcalase to obtain casein hydrolysates, with a hydrolysis degree of 12.6% and an in vitro ACE inhibitory activity of 48.2%. The hydrolysates were modified by alcalase-catalyzed plastein reaction in propanol-water medium. The effects of reaction temperature, enzyme dosage, substrate concentration, propanol concentration on the reaction were studied. The reaction conditions were optimized by response surface methodology as reaction temperature of 47℃, enzyme dosage of 8.3 kU/g proteins, substrate concentration of 56.8 g/100 mL, propanol concentration of 58.5% (v/v). Five modified products wim different reaction extent were prepared and their ACE inhibitory activities were assayed, which showed that one modified product had the highest activity about 63.8%. It was also showed that addition of phenylalanine or tyrosine into the reaction system would induce increase or decrease in the activity of the modified product slighdy, compared to the plastein reaction of the hydrolysates without amino acid addition.%利用碱性蛋白酶水解酪蛋白,制备出水解度为12.6％、ACE抑制活性为48.2％的酪蛋白水解物.利用碱性蛋白酶、在丙醇-水介质中进行类蛋白反应修饰酪蛋白水解物,研究反应温度、酶添加量、底物质量浓度、丙醇浓度对修饰反应的影响.响应面法试验设计,得到最优条件为反应温度47℃、酶添加量8.3 kU/g,底物质量浓度56.8 g/100 mL,丙醇体积分数58.5％.利用此条件制备出的反应程度不同的5个修饰产物,ACE抑制活性分析结果显示,抑制活性最高可以达到63.8％.在相应条件下加入酪氨酸或苯丙氨酸,对比试验结果显示,添加苯丙氨酸或酪氨酸会导致修饰产物抑制活性增加或降低.
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