Oxidation and reduction of cytochrome c by mitochondrial enzymes of Setaria cervi.

A mitochondria-rich fraction isolated from the cuticle-hypodermis-muscle system of Setaria cervi, a bovine filarial parasite, possessed substrate-coupled cytochrome c reductases and cytochrome c oxidase in appreciable activities. All these activities were located predominantly in the membranes. NADH-coupled cytochrome c reductase was more prominent than NADPH- and succinate-coupled reductases. All the three reductases exhibited marked sensitivity to rotenone and antimycin A. Salicylhydroxamic acid strongly inhibited succinate requiring reductase and cytochrome c oxidase, but the other two reductases only mildly. Sodium azide activated the reductases but substantially inhibited the oxidase activity. Potassium cyanide activated the succinate requiring reductase but did not cause any noticeable change in the activities of pyridine nucleotide linked reductases. Anthelmintics also influenced these activities but no definite correlation could be drawn regarding their mode of action.