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.

Pathology associated with Contracaecum rudolphii (Nematoda: Anisakidae) infection in the great cormorant Phalacrocorax carbo (L. 1758)

“…They aid in organ penetration by digesting the connective tissue matrix, provide an immunoprotective mechanism, are anticoagulants, facilitate larval molting, and play a major role in external digestion and nutrient uptake by the parasites (Knox & Kennedy, 1988;Moczoń & Wranicz, 1999). A similar role is played by other, nonproteolytic enzymes within the SP, including hyaluronidases (Hotez et al, 1994), leucine-aminopeptidase (Rhoads et al, 1997), acetylocholinesterases (Opperman & Chang, 1992) and other hydrolases (Dziekońska-Rynko et al, 2003). Studies by Dziekońska-Rynko and Rokicki (2005) failed to document the presence of endoproteases in the SP products from adult C. rudolphi, but high levels of leucineaminopeptidase, and different esterases and glycosidases were detected.…”

Release of hyaluronidase during in vitro development of Ascaris suum from the third to fourth larval stage

“…In Ascaris suum, a 293-kDa aminopeptidase was shown to be released into culture¯uid during development of L3 to L4 in vitro, with the peak level of secretion temporally associated with molting (Rhoads et al 1997). A role for a cysteine protease in the development of A. suum from L3 to L4 was also suggested by studies demonstrating the inhibition of this development by Z-phe-ala-FMK, a speci®c inhibitor of the cysteine class of proteases .…”

Cloning and analysis of a cDNA encoding a putative serine protease comprising two trypsin-like domains of Trichinella spiralis

“…Proteases from other parasites have been shown to be involved in this essential process of moulting. Aminopeptidase activity was identified during in vitro development of the L3 to L4 larval stages of Ascaris suum (Rhoads et al 1997), and peak secretion of the enzyme was correlated with moulting, thus demonstrating its involvement. Metalloproteases of H. contortus (Gamble et al 1996) and metalloproteases associated with cysteine proteases of Dirofilaria immitis (Richer et al 1992) have also been suggested to play a role in the moulting process and in the degradation of cutaneous tissue components.…”