细胞膜毒素对线粒体上钙通道的抑制

本文探讨膜毒素对鼠肝线粒体Ca~(++)传递和Ca~(++)结合亲和力的影响。当膜毒素的浓度为7.14毫微克分子/毫克线粒体蛋白时,处理过的线粒体传递Ca~(++)能力下降至原来一半左右。本实验做Ca~(++)结合膜毒素处理线粒体的Scatchard图呈直线(K_d=48.2μM,结合Ca~(++)数目N=341毫微克分子/毫克线粒体蛋白)。就是说,膜毒素抑制线粒体高亲和力Ca~(++)结合部位,而不影响低亲和力Ca~(++)结合部位。我们认为膜毒素作用位点在于线粒体高亲和力Ca~(++)结合部位。

THE EFFECT OF MEMBRANE TOXIN (Naja naja atra) OH Ca~(++) CHANNEL OF RAT LIVER MITOCHONDRIA

THe effect of membrane toxin-c (MT-C) on Ca++ -binding and transport in rat liver mitochondria has been studied.The Ca++-binding capacity to the rat liver mitochondria is lowered to an extent of 50% at a concentration of 7. 14 nmole MT-C/ mg mitochondrial protein. Linear relationship has been observed on Scatchard plots of Ca++-binding in the presence of MT-C (Kd: 48.2 uM; number of Ca++-binding sites. 341 nmol/ nag mho.), i. e., MT-C inhibited the high-affinity Ca++-binding sites, but did not interfere with the low-affinity Ca++-binding sites. Our result suggest that the site of action of MT-C on rat liver mitochondria can be mainly ascribed to the high affinity site of Ca++-binding on the inner membrane.