Parasitology Research

, Volume 80, Issue 8, pp 680–683 | Cite as

A cysteine proteinase in the cercariae ofDiplostomum pseudospathaceum (Trematoda, Diplostomatidae)

  • T. Moczoń
Original Paper


A cysteine proteinase was detected in extracts from cercariae of the trematodeDiplostomum pseudospathaceum. The enzyme preferred protein substrates over synthetic, chromogenic peptides. The optimal pH for hydrolysis of substrates was 7.2 for azocoll, 6.4 and 7.6 for azocasein, 7.6 for azoalbumin, and 6.8 forN-benzoyl-l-arginine-4-nitroanilide. Elastin-Congo red and certainN-blockedl-aminoacyl-andl-peptidyl nitroanilides bearingl-phenylalanine,l-alanine,l-tyrosine, andl-leucine at the P1 subsite were not hydrolyzed. Thiol-reducing and divalent cation-complexing agents stimulated the proteinase activity, whereas thiol-blocking agents inhibited it. The relative molecular weight of the enzyme was approximately 40 000 as determined by SDS-PAGE. Detection of an identical proteinase in water after treatment of living cercariae with praziquantel suggests that the enzyme occupied the penetration glands in the larvae. Thus, when secreted by the parasite during invasion of an appropriate host, the enzyme might act as a penetration-promoting factor.


Peptide Molecular Weight Cysteine Proteinase Activity Cysteine Proteinase 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



sodium dodecyl sulfatepolyacrylamide electrophoresis


bovine serum albumin




ethylene glycol-O,OO′-bis(2-aminoethyl)N,N,N′,N′-tetraacetic acid








phenylmethanesulfonyl fluoride


tosyl-l-phenylalanine chloromethyl ketone


tosyl-l-lysine chloromethyl ketone


soybean trypsin inhibitor


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Copyright information

© Springer-Verlag 1994

Authors and Affiliations

  • T. Moczoń
    • 1
  1. 1.Institute of ParasitologyPolish Academy of SciencesWarsawPoland

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