Reversible Effect of Calcium-Binding Protein on the Ca^<2+>-Induced Activation of Succinate Dehydrogenase in Rat Liver Mitochondoria(Biological)

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The effect of calcium-binding protein (CaBP) isolated from rat liver cytosol on the Ca^<2+>-induced increase in succinate dehydrogenase activity of rat liver mitochondria was investigated. The liver mitochondrial succinate dehydrogenase activity was significantly increased by addition of Ca^<2+> in the range of 1.0-50μM. Of various other metals (25μM) tested, addition of Hg^<2+>, Zn〜<2+> and Cd^<2+> caused a significant decrease in succinate dehydrogenase activity of the hepatic mitochondria, while Mg^<2+>, Mn^<2+> and Sr^<2+> had no effect; the increase in the enzyme activity was specific for Ca^<2+>. This Ca^<2+>-induced increase in the mitochondrial succinate dehydrogenase activity was completely blocked by the presence of ruthenium red (10 and 50 μM), an inhibitor of mitochondrial Ca^<2+> uptake, indicating that Ca^<2+> was transported into the mitochondria and activated the enzyme there. In the presence of more than 7.0μM CaBP, the Ca^<2+> (10μM)-induced increase in succinate dehydrogenase activity was completely reversed, but 1.4μM CaBP had no effect on this increase. CaBP itself (15μM) did not have an inhibitory effect on the basal activity of succinate dehydrogenase. The present results suggest that CaBP regulates the increase in succinate dehydrogenase activity by blocking Ca^<2+> transport into the hepatic mitochondria of rats.
公益社団法人日本薬学会の論文
1987-09-25