title: Entamoeba histolytica and E. invadens: sulfhydryl-dependent proteolytic activity.
abstract: Sodium dodecyl sulfate (SDS) and 2-mercaptoethanol (2-ME) activated proteolytic enzymes present in extracts of Entamoeba histolytica and E. invadens; SDS (0.5%) and 2-ME (1.4 and 715 mM) doubled the enzymatic activity when assayed on a stained insoluble substrate. Urea (4 M) did not reduce this activity, suggesting that amebic proteases are stable in the above denaturant conditions. Specific reagents for sulfhydryl (-SH) groups completely inhibited proteolytic activity regardless of pH. Inhibition with alkylating agents, such as N-ethylmaleimide and iodoacetamide, was reversed with 715 mM 2-ME as was also observed with papain. We conclude from these results that the main proteolytic enzymes contained in extracts of E. histolytica and E. invadens are dependent on free thiol groups.
authors.forename: E E
authors.initials: EE
authors.lastname: Avila
authors.forename: M
authors.initials: M
authors.lastname: Sánchez-Garza
authors.forename: J
authors.initials: J
authors.lastname: Calderón
mesh_terms: D000818:Animals; D003546:Cysteine Endopeptidases; D010450:Endopeptidases / Q000378:metabolism*; D004747:Entamoeba / Q000201:enzymology*; D004748:Entamoeba histolytica / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D008623:Mercaptoethanol / Q000494:pharmacology; D011480:Protease Inhibitors; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D014508:Urea / Q000494:pharmacology
chemical_list: D011480:Protease Inhibitors; D013439:Sulfhydryl Reagents; D012967:Sodium Dodecyl Sulfate; D008623:Mercaptoethanol; D014508:Urea; D010450:Endopeptidases; D003546:Cysteine Endopeptidases