Biochemistry of the dog hookworm. I. Oxidative metabolism

The respiration of Ancylostoma caninum was found to be inhibited by cyanide. Evidence for the presence of tricarboxylic acid cycle enzymes in this organism has been adduced from data on the worms' ability to oxidize pyruvic and succinic acids. Succinic dehydrogenase activity was observed in mitochondria obtained from adult male and female worms. Mitochondrial purity of the suspensions utilized was verified by electron microscopy. A succinoxidase system was detected, and the respiration of this system was inhibited by malonate. The inhibition could be reversed by increasing the succinate concentration. Succinic dehydrogenase activity was also assayed by a methylene blue reduction technique. Using the methylene blue-reduction assay, the pH optimum of the dehydrogenase was 9.