Structural analysis and demonstration of the 29 kDa antigen of pathogenic Entamoeba histolytica as the major accessible free thiol‐containing surface protein

Becky M. Flores, Idaho State University
Mark A. Batzer, Lawrence Livermore National Laboratory
Murry A. Stein, Idaho State University
Carolyn Petersen, University of California, San Francisco
Dana L. Diedrich, Idaho State University
Bruce E. Torian, Idaho State University


The 29 kDa protein of pathogenic Entamoeba histolytica is a cysteine‐rich surface antigen which we recently characterized by cDNA sequencing and by using monoclonal antibodies which differentiated between pathogenic and non‐pathogenic clinical isolates. To determine the structure and biochemical attributes of this protein, a repertoire of immunologcal techniques using monoclonal antibodies, and radiolabelling were employed. We demonstrated that the 29 kDa protein forms a 60 kDa dimer and a high‐molecular‐mass oligomer(s) on the surface of the organism through disulphide bonds, and is the major accessible free thiol‐containing surface protein of E. histolytica. The deduced amino acid sequence encoding the 29 kDa protein was found to share a common amino acid domain with sequences reported for Helicobacter pylori, Salmonella typhimurium, MER5 gene expressed in murine erythroleukemia cells, Clostridium pasteurianum, and a Bacillus spp. Copyright © 1993, Wiley Blackwell. All rights reserved