A casein hydrolysate with a degree of hydrolysis of 11.6％ was prepared by Alcalase,and had ACE inhibition with an IC50 value of 42.8 mg/L.The casein hydrolysate was modified by Alcalase-catalyzed plastein reaction in ethanol-water medium.The reaction time was fixed at 6 h,and the optimal Alcalase addition,ethanol and substrate concentration or reaction temperature fiom experimental design were 8.36 kU/g,568 g/L,56.8％ or 37.5 ℃,respectively.Some of treated casein hydrolysates with different reaction extent were prepared to evaluate their ACE-inhibition.and zinc chelating ability.The result indicated that the ACE-inhibition of the modified casein hydrolysates were enhanced by the carried out plastein reaction but depended on the reaction extent.One modified casein hydrolysate showed the highest ACE-inhibition of 62.5％ and an IC50 of 27.7 mg/L.However,the zinc chelating ability of these modified casein hydrolysates were decreased from 4.22 mg/g to 1.97～3.86 mg/g.It was also found that zinc chelating ability of the modified casein hydrolysates had no relationship to their reaction extent as well as ACE inhibition.%利用Alcalase水解酪蛋白,制备水解度为11.6％、IC5值为42.8 mg/L的酪蛋白水解物.在乙醇-水体系中采用Alcalase催化类蛋白反应修饰酪蛋白水解物,固定反应时间6h,优化得到酶添加量、乙醇体积分数、底物质量浓度、反应温度分别为:8.36 kU/g,56.8％,568 g/L,37.5℃.制备不同反应程度的修饰产物,评估其ACE抑制活性及Zn2+螯合能力变化,发现修饰产物的ACE抑制活性得到改善,抑制最高达到62.5％(IC50达到27.7 mg/L),但是与反应程度有关；Zn2+螯合能力则由4.22 mg/g降低至1.97～3.86 mg/g.修饰产物的Zn2+螯合能力与类蛋白反应程度无关,与ACE抑制活性也不存在相关性.
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