title: Secretion of an aminopeptidase during transition of third- to fourth-stage larvae of Ascaris suum.
abstract: Protease activity was identified in culture fluids collected during in vitro 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. 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 was estimated by sucrose density gradient centrifugation at 293 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 protease in this complex process.
authors.affiliation: Parasite Biology & Epidemiology Laboratory, United States Department of Agriculture, Beltsville, Maryland 20705, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Rhoads
authors.forename: R H
authors.initials: RH
authors.lastname: Fetterer
authors.forename: J F
authors.initials: JF
authors.lastname: Urban
mesh_terms: D000626:Aminopeptidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D017165:Ascaris suum / Q000201:enzymology* / Q000254:growth & development; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007526:Isoelectric Point; D007814:Larva / Q000201:enzymology / Q000254:growth & development; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D008970:Molecular Weight; D010455:Peptides; D010618:Phenanthrolines / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology; D013379:Substrate Specificity; D013552:Swine
chemical_list: D000900:Anti-Bacterial Agents; D010455:Peptides; D010618:Phenanthrolines; D011480:Protease Inhibitors; C016977:amastatin; D000626:Aminopeptidases; D007930:Leucine; C012211:ubenimex; C025205:1,10-phenanthroline