[Characterization of surface molecules of Entamoeba invadens]

In this paper we studied the externally disposed plasma membrane antigens in Entamoeba invadens using the enzymatic iodination technique. Sodiumdodecyl-sulfate-polyacrylamide gels of solubilized trophozoite proteins revealed six labeled peaks ranging from 14,000 to 67,000 daltons in gradient slab gels. Over 60 percent of the labeled was in the polypeptide of 67,000 daltons. Concanavalin A binding to these trophozites induced cell surface coat release consituted by three radioactive bands of 67,000, 60,000 and 24,000 daltons. Using an affinity chromatography method with Con A conjugated to Sepharose 4B, trophozoites in culture mixture with these beads during three hours at 22 degree C, released three components that were eluted from immobilized Con A, 67,000, 60,000 and 56,000 daltons revealed in gradient slab gels. In several determinations, the 67,000 daltons glycoprotein consistently was the major surface component, and the most immunogenic as analyzed from rabbits sera immunized with whole cell extracts as well with cell surface coat.