Isolation and Analysis of the Lipid A Backbone

Abstract

A degradation procedure of lipopolysaccharides was worked out which allows the isolation of the reduced backbone of lipid A in a total yield of between 20 and 30%. This procedure was applied to lipopolysaccharides of S forms (Salmonella minnesota, Shigella flexneri 5b, Escherichia coli 086, E. coli 0111, Xanthomonas sinensis, Rhodopseudomonas gelatinosa) and R mutants (Salmonella minnesota, Shigella flexneri, 5b, E. coli BB9 and E. coli EH 100). Chemical analysis, reaction with beta-N-acetyl-glucosaminidase and application of methylation analysis revealed that the lipid A backbone of all strains contains beta 1', 6-linked glucosamine disaccharides carrying two phosphate groups, one in glycosidic and one in ester linkage, a structure, identified previously in the Salmonella minnesota Re mutant.