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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 4144

Eva E. Avila, Mireya Sanchez-Garza, and Jesus Calderon; Entamoeba histolytica and E. invadens: Sulfhydryl-Dependent Proteolytic Activity. J.Protozool. 32(1):163-166, 1985

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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.