A LECTIN ACTIVITY IN ENTAMOEBA-HISTOLYTICA TROPHOZOITES

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  • 1 January 1980
    • journal article
    • research article
    • Vol. 11, 101-108
Abstract
A lectin (carbohydrate binding protein) was found in extracts of a number of axenically grown trophozoites of E. histolytica strains. The strains grown in Diamond''s TYI-S-33 media were HK-9, 200:NIH and HM-1:IMSS. Strain HU-1:MUSC (HSC) was grown monoxenically in the same medium. The amoeba lectin agglutinates glutaraldehyde-fixed red blood cells. This activity is pH-dependent, heat- and oxidation-sensitive and is destroyed by proteolysis upon auto-incubation. The relative agglutinating potency of the different strains was investigated. Strain HSC had the highest specific activity (210 U/mg protein) and strain HM-1 the lowest (14 U/mg). A unit of hemagglutinating activity is defined as the amount of lectin present in 1 ml of extract which will agglutinate 1 ml of 4% [human] red blood cells. Upon subcellular fractionation of the lectin present in extracts of strain HK-9, 2/3 of the activity were detected in the soluble, non-sedimentable (100,000 g, 60 min) fraction. Partial hydrolysate of chitin inhibited the hemagglutinating activity. Among the oligosaccharides of N-acetylglucosamine, the trimer and tetramer were the most potent inhibitors. The lectin was purified approximately 300-fold by a 1-step affinity chromatography on a chitin column. The loading and elution from the column were based on the pH dependence of lectin activity.