The content of calpain II is 3.4 times more than that of calpain I when estimated by the elution profiles from a column of DEAE-cellulose. 2. Calpain I required 1 mM Ca2+ and calpain II required 5 mM Ca2+ to show the full activities. These data demonstrated that Ca2+-sensitivities of both calpains were lower than those of mammalian calpains, respectively. 3. The optimum caseinolytic activity was pH 7.2 for calpain I and pH 7.5 for calpain II. 4. The molecular weight of calpain I was estimated to be 110 k and that of calpain II to be 120 k by gel filtration. 5. Calpain I was much more heat-stable than calpain II around 50-60 degrees C. 6. Both calpains were sensitive to calpastatin, an endogenous inhibitor for calpain.
摘要
通过DEAE - 纤维素柱的洗脱曲线估算，钙蛋白酶II的含量比钙蛋白酶I多3.4倍。2. 钙蛋白酶I需要1 mM Ca2+，钙蛋白酶II需要5 mM Ca2+才能表现出完全活性。这些数据表明，两种钙蛋白酶对Ca2+的敏感性分别低于哺乳动物钙蛋白酶。3. 钙蛋白酶I的最佳酪蛋白水解活性pH为7.2，钙蛋白酶II为pH 7.5。4. 通过凝胶过滤法估算，钙蛋白酶I的分子量为110 k，钙蛋白酶II为120 k。5. 在50 - 60摄氏度左右，钙蛋白酶I比钙蛋白酶II更耐热。6. 两种钙蛋白酶都对钙蛋白酶抑制蛋白敏感，钙蛋白酶抑制蛋白是钙蛋白酶的一种内源性抑制剂。
