OXIDATION AND REDUCTION OF CYTOCHROME-C BY MITOCHONDRIAL-ENZYMES OF SETARIA-CERVI

A mitochondria-rich fraction isolated from the cuticle-hypodermis-musc le system of Setaria cervi, a bovine filarial parasite, possessed subs trate-coupled cytochrome c reductases and cytochrome c oxidase in appr eciable 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. Salicylhydr oxamic acid strongly inhibited succinate requiring reductase and cytoc hrome c oxidase, but the other two reductases only mildly. Sodium azid e activated the reductases but substantially inhibited the oxidase act ivity. Potassium cyanide activated the succinate requiring reductase b ut did not cause any noticeable change in the activities of pyridine n ucleotide linked reductases. Anthelmintics also influenced these activ ities but no definite correlation could be drawn regarding their mode of action.