Histochemistry of proteinases in the cercariae of Diplostomum pseudospathaceum (Trematoda, Diplostomatidae).
Two distinct endopeptidases were detected histochemically in the cercariae of Diplostomum pseudospathaceum: a serine proteinase occupying the ceca and a cysteine proteinase occupying the penetration glands. The former was relatively resistant to formaldehyde, required either Ca2+ or Mg2+ for its stability, and was sensitive to organic fluorophosphate inhibitors but insensitive to thiol-blocking agents. The latter enzyme required both reducing and divalent cation-complexing agents for its full activity and was sensitive to formaldehyde, thiol-blocking agents, and diazonium salts. Both enzymes hydrolyzed a number of N-blocked L-aminoacyl-, and N-blocked L-peptidyl-naphthylamides bearing L-arginine at the P1 subsite. The pH optima for hydrolysis of the substrates were 8.0 for the serine proteinase and 7.6 for the cysteine proteinase.
Moczoń
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Institute of Parasitology, Polish Academy of Sciences, Warsaw.
D000818:Animals; D003546:Cysteine Endopeptidases / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism*; D006651:Histocytochemistry; D006863:Hydrogen-Ion Concentration; D007814:Larva / Q000033:anatomy & histology / Q000201:enzymology; D012697:Serine Endopeptidases / Q000378:metabolism; D013379:Substrate Specificity; D014200:Trematoda / Q000033:anatomy & histology / Q000201:enzymology*
D010450:Endopeptidases; D012697:Serine Endopeptidases; D003546:Cysteine Endopeptidases