Polyamine metabolism in Ancylostoma ceylanicum and Nippostrongylus brasiliensis.

Abstract Polyamine metabolism in Ancylostoma ceylanicum and Nippostrongylus brasiliensis. International Journal for Parasitology 19: 191–198. Spermidine was detected as the major polyamine of Ancylostoma ceylanicum as well as Nippostrongylus brasiliensis . Spermine was present in lower amounts whereas the level of putrescine was even less. S -Adenosylmethionine decarboxylase, a rate-limiting enzyme in the biosynthetic pathway of polyamines, was demonstrated at low levels in both parasites. Decarboxylation of lysine and arginine was absent or negligible and that of ornithine questionable, as the enzyme activity was not inhibited by α-difluoromethylornithine while RMI 71 645, an irreversible inhibitor of ornithine aminotransferase, strongly inhibited the liberation of CO 2 from ornithine. High activity of ornithine aminotransferase was observed in both the parasites and may interfere with the assay for ornithine decarboxylase. Adults of A. ceylanicum were found to rapidly take up spermidine and spermine from incubation medium while uptake of putrescine was very low. These results indicate that hookworms depend on uptake and interconversion rather than de novo synthesis for their polyamine requirement.