Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 21, 1997
Publication Date: N/A
Interpretive Summary: The swine round worm, Ascaris suum, is responsible for significant economic losses by reducing production efficiency and causing organ condemnations at slaughter due to pathology produced by parasite larval stages. Development of novel controls can be enhanced by a knowledge of the biochemical mechanism underlying the process of molting, an essential process in the growth and development of all nematodes. The results demonstrate that A. suum produce an enzyme coincident with molting. Inhibition of this enzyme activity may interfere with the molting process.
Technical Abstract: Neutral protease activity was identified in culture fluids collected during development of L3 to L4 larval stages of Ascaris suum. Fluorogenic peptide substrates with unblocked N-termini were specifically hydrolyzed indicating aminopeptidase activity; a terminal arginyl residue was preferred. L3/L4 culture fluids did not hydrolyze fluorogenic peptide substrates with blocked N-termini (endopeptidase substrates). The aminopeptidase activity was inhibited by 1,10- phenanthroline (metalloprotease inhibitor) and by amastatin and bestatin (aminopeptidase inhibitors); AEBSF (serine protease inhibitor), Z-phe- ala-FMK and E-64 (cysteine protease inhibitors), and pepstatin A (aspartyl protease inhibitor) had little effect on activity. The apparent molecular weight of the aminopeptidase estimated by sucrose density gradient centrifugation was 252 kDa. The aminopeptidase displayed an acidic isoelectric point of 4.7. The peak secretion of the aminopeptidase was temporally associated with molting and suggests a function for the enzyme in this complex process.