中文摘要：

通过DEAE-Sephadex A-25和Sephadex G-100对干酪乳杆菌胞壁蛋白酶粗提物进行分离纯化,分离到酶比活力为12.50U/mg的CEP-1与16.67U/mg的CEP-2两种胞壁蛋白酶。CEP-1提纯倍数达到50,回收率为33.61%;CEP-2提纯倍数为66.68,回收率55.17%。对不同时间和底物浓度下CEP-1与CEP-2的α-酪蛋白和β-酪蛋白水解特性进行研究。结果显示,酪蛋白水解产物有显著的抗ACE与抗氧化活性,产生最高ACE抑制活性的水解条件为：CEP-2水解α-酪蛋白,时间6h,酶与底物质量比1：10,此时ACE抑制活性为84.66%;在酶与底物质量比1：40,水解时间4h条件下,CEP-2水解β-酪蛋白产生最佳的O-2.清除能力,其IC50为0.2138mg/mL。

英文摘要：

Crude cell-envelop proteinase extracted from Lactobacillus casei cells was purified/fractionated by DEAE-Sephadex A-25 and subsequent Sephadex G-100 column chromatographies.Two cell-envelop proteinase fractions,named as CEP-1 and CEP-2,were obtained,of which the activity was 12.50 U/mg and 16.67 U/mg,the purification folds 50 and 66.68,and the recoveries 33.61% and 55.17%,respectively.The hydrolysis characteristics of CEP-1 and CEP-2 on α-casein and β-casein under different conditions of hydrolysis time and substrate concentration were assessed in terms of angiotensin-I-converting enzyme（ACE） inhibitory activity and superoxide anion radical scavenging activity of hydrolysates.Both CEP fractions resulted in casein hydrolysates with obvious ACE inhibitory activity and superoxide anion radical scavenging activity.Maximum ACE inhibitory activity was achieved after 6 h hydrolysis of α-casein at an enzyme/substrate ratio of 1：10 by CEP-2,reaching 84.66%.Theβ-casein hydrolysate obtained after 4 h of hydrolysis with an enzyme/substrate ratio of 1：40 revealed the best superoxide anion radical scavenging activity with a 0.2138 mg/mL IC50.