title: Isolation, partial purification and some properties of two acid proteases from adult Dirofilaria immitis.
abstract: Two acid proteases were isolated from the soluble extracts of adult Dirofilaria immitis, the filarial heartworm of canines. Activity of these proteases was detected using 3H-labeled bovine alpha-casein as substrate, and they were designated Fp-I and Fp-II in order of their elution from a CM-cellulose column. The molecular weight of partially purified Fp-I was approximately 170000, and it was active between pH 4.6-5.8. The activity of Fp-I doubled in the presence of various sulfhydryl reagents at 5 mM, and it was inhibited 50-60% by the sulfhydryl inhibitors p-hydroxymercuribenzoate and iodoacetate at 1 mM, the heavy metal chelating agent o-phenanthroline at 1 mM and the peptide aldehyde protease inhibitors pepstatin (10 microM), leupeptin, antipain and chymostatin (50 microM). The molecular weight of the more extensively purified Fp-II is approximately 48000. This protease was active between pH 2.6-3.4 and was highly sensitive to inhibition by pepstatin (80% inhibition at 10 nM). Fp-II was not significantly affected by sulfhydryl reagents, sulfhydryl inhibitors, metal chelating agents or peptide aldehyde protease inhibitors other than pepstatin. These properties of dirofilarial Fp-II resemble those of mammalian cathepsin D.
mesh_terms: D000818:Animals; D002614:Chelating Agents / Q000494:pharmacology; D055598:Chemical Phenomena; D002621:Chemistry; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D004183:Dirofilaria immitis / Q000201:enzymology*; D005370:Filarioidea / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D010447:Peptide Hydrolases / Q000302:isolation & purification*; D011480:Protease Inhibitors / Q000494:pharmacology; D013439:Sulfhydryl Reagents / Q000494:pharmacology
chemical_list: D002614:Chelating Agents; D011480:Protease Inhibitors; D013439:Sulfhydryl Reagents; D010447:Peptide Hydrolases