title: High-molecular-weight components in lipopolysaccharides of Salmonella typhimurium, Salmonella minnesota, and Escherichia coli.
abstract: Lipopolysaccharide from smooth strains of Salmonella typhimurium, Salmonella minnesota, and Escherichia coli O111:B4, O55:B5, and O127:B8 was fractionated by gel filtration chromatography. All lipopolysaccharide samples separated into three major populations. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the fractions from S. typhimurium and S. minnesota indicated that the three peaks were made up of molecules with average O-antigen lengths of (i) 70 or more repeat units, (ii) 30 and 20 repeats units in the samples from S. typhimurium and S. minnesota, respectively, and (iii) 1 repeat unit. In contrast to the Salmonella samples, peak 1 from the E. coli samples was not detected on polyacrylamide gels and lacked detectable phosphate. This high-molecular-weight material had a sugar composition similar to that of O-antigen and was tentatively identified as capsular polysaccharide. Peaks 2 and 3 of the E. coli samples were analogous to those of the Salmonella isolates, containing lipopolysaccharide molecules with averages of 18 and 1 O-antigen repeat units, respectively. These lipopolysaccharide molecules did not completely dissociate during electrophoresis, and multimers were detected as distinct, anomalous, slow-migrating bands. Increasing the concentration of sodium dodecyl sulfate in the gels resulted in the dissociation of these multimers.
mesh_terms: D000942:Antigens, Bacterial / Q000032:analysis; D002850:Chromatography, Gel; D004926:Escherichia coli / Q000032:analysis* / Q000276:immunology; D008070:Lipopolysaccharides / Q000032:analysis*; D046911:Macromolecular Substances; D008970:Molecular Weight; D012475:Salmonella / Q000032:analysis* / Q000276:immunology; D012486:Salmonella typhimurium / Q000032:analysis* / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial; D008070:Lipopolysaccharides; D046911:Macromolecular Substances