Grasso M, Morelli A, De Flora A
Biochem Biophys Res Commun. 1986 Jul 16;138(1):87-94. doi: 10.1016/0006-291x(86)90250-0.
Human red cells were treated with 100 microM Ca2+ and ionophore A 23187. This treatment induces remarkable changes in the activities of the two major proteolytic systems of red cells, i.e. Ca2+-dependent neutral proteinase and acid endopeptidases. Ca2+-dependent neutral proteinase undergoes intracellularly preliminary activation of the inactive proenzyme species, followed by eventual inactivation through self-proteolysis. Transient activation is shown by selective degradation of cytoskeletal proteins known to be targets of this enzyme system. Concomitantly, acid endopeptidase activity is substantially released from the membrane into the cytosol. Preliminary inactivation of the Ca2+-dependent neutral proteinase by exposure of Glucose 6-phosphate dehydrogenase-deficient red cells to auto-oxidizing divicine prevents alterations induced by Ca2+ loading on cytoskeletal membrane proteins, while leaving solubilization of acid endopeptidase activity unaffected. The two events, although dependent on Ca2+ loading, are therefore unrelated to each other.
将人类红细胞用100微摩尔的Ca2+和离子载体A 23187进行处理。这种处理会引起红细胞两个主要蛋白水解系统，即Ca2+依赖性中性蛋白酶和酸性内肽酶活性的显著变化。Ca2+依赖性中性蛋白酶在细胞内经历无活性酶原的初步激活，随后通过自我蛋白水解最终失活。短暂激活表现为已知该酶系统作用靶点的细胞骨架蛋白的选择性降解。同时，酸性内肽酶活性从膜大量释放到细胞质中。通过将葡萄糖6-磷酸脱氢酶缺陷的红细胞暴露于自氧化的异豆碱中使Ca2+依赖性中性蛋白酶初步失活，可防止Ca2+加载对细胞骨架膜蛋白的诱导改变，而酸性内肽酶活性的溶解不受影响。因此，这两个事件虽然都依赖于Ca2+加载，但彼此无关。
