Rakhimov M M, Kkholé V, Babaev M U, Tashmukhamedov B A
Biokhimiia. 1981 Mar;46(3):453-61.
The effects of Ca2+ and cytotoxin from Middle Asian cobra venom on the hydrolytic activity of phospholipase A2 from the same source and on its action on erythrocyte membrane phospholipids and mitochondria were studied. The necessity of phospholipase A2 for Ca2+ depends on the type of substrates (phosphatidyl methanol, phosphatidyl ethanol, cephalin, phosphatidyl ethyleneglycol, phosphatidyl inositol), whereas enzymatic cleavage of lecithin can also occur in the absence of Ca2+. Cytotoxin Vc" I had no effect on the rate of phospholipid hydrolysis in the absence of Ca2+. However, in the presence of Ca2+ cytotoxin at low concentrations activated phospholipase A2, while its high concentrations inhibited the phospholipid hydrolysis with the exception of phosphatidyl ethyleneglycol and phosphatidyl inositol. In experiments with purified phospholipids no synergistic effect of cytotoxin and phospholipase A2 was observed. The activating effect of cytotoxin and phospholipase A2 was comparable to that of the cationic detergents. The effect of phospholipase A2 on erythrocyte hemolysis and succinate oxidation by mitochondria was more complicated: the activating or inhibiting effect depended on the state and ratio of Ca2+, cytotoxin and phospholipase A2. It is suggested that the synergistic effect observed in membrane systems is primarily due to the structural organization of the membranes and the phase condition of the membrane phospholipids.
研究了中亚眼镜蛇毒中的钙离子和细胞毒素对同来源磷脂酶A2水解活性的影响，以及其对红细胞膜磷脂和线粒体的作用。磷脂酶A2对钙离子的需求取决于底物类型（磷脂酰甲醇、磷脂酰乙醇、脑磷脂、磷脂酰乙二醇、磷脂酰肌醇），而卵磷脂的酶促裂解在无钙离子时也可发生。细胞毒素Vc“ I在无钙离子时对磷脂水解速率无影响。然而，在有钙离子存在时，低浓度的细胞毒素可激活磷脂酶A2，而高浓度时除磷脂酰乙二醇和磷脂酰肌醇外，可抑制磷脂水解。在用纯化磷脂进行的实验中，未观察到细胞毒素与磷脂酶A2的协同作用。细胞毒素和磷脂酶A2的激活作用与阳离子去污剂相当。磷脂酶A2对红细胞溶血和线粒体琥珀酸氧化的影响更为复杂：激活或抑制作用取决于钙离子、细胞毒素和磷脂酶A2的状态及比例。有人提出，在膜系统中观察到的协同作用主要归因于膜的结构组织和膜磷脂的相状态。
