Murakami T, Ueda M, Hamakubo T, Murachi T
Department of Home Economics, Kyoto Bunkyo Junior College.
J Biochem. 1988 Jan;103(1):168-71. doi: 10.1093/oxfordjournals.jbchem.a122225.
Chicken erythrocytes were found to contain two species of calpains which differ in elution profile from DEAE-cellulose and in Ca2+ requirement. After partial purification, one of them was half-maximally activated by 10 microM Ca2+ and the other by 180 microM Ca2+. The low- and high-Ca2+-requiring proteases cross-reacted only with the respective monospecific antibodies for mammalian calpain I and calpain II, respectively. Approximately 5 times more calpain I than calpain II is present in chicken erythrocytes. By immunoelectrophoretic blot analysis, both calpains I and II from chicken erythrocytes were proved to be heterodimers composed of 76 and 28 kDa, and 80 and 28 kDa subunits, respectively. Our present finding that the heavy subunit of calpain I is smaller than that of calpain II is noteworthy, since the opposite is known to be true of various mammalian calpains. An immunological study has revealed that the calpain I newly found in chicken erythrocytes is not derived from calpain II. Thus, the co-existence of calpains I and II in one animal species also holds in chickens, contrary to the previously advocated notion that chickens have only one type of calpain.
已发现鸡红细胞含有两种钙蛋白酶，它们在从DEAE - 纤维素上的洗脱图谱和对Ca2 +的需求方面存在差异。经过部分纯化后，其中一种在10微摩尔Ca2 +时达到最大活性的一半，另一种在180微摩尔Ca2 +时达到最大活性的一半。需要低Ca2 +和高Ca2 +的蛋白酶分别仅与针对哺乳动物钙蛋白酶I和钙蛋白酶II的各自单特异性抗体发生交叉反应。鸡红细胞中钙蛋白酶I的含量比钙蛋白酶II大约多5倍。通过免疫电泳印迹分析，证明鸡红细胞中的钙蛋白酶I和II均为异二聚体，分别由76 kDa和28 kDa以及80 kDa和28 kDa亚基组成。我们目前发现钙蛋白酶I的重亚基比钙蛋白酶II的小，这一点值得注意，因为已知各种哺乳动物钙蛋白酶的情况与此相反。一项免疫学研究表明，在鸡红细胞中新发现的钙蛋白酶I并非源自钙蛋白酶II。因此，与之前所主张的鸡只有一种钙蛋白酶的观点相反，鸡这种动物物种中也同时存在钙蛋白酶I和II。
