Deacylation of Lipopolysaccharides and Isolation of Oligosaccharide Phosphates

Two types of lipopolysaccharides (LPS) exist: smooth (S) and rough (R) forms (1–3). Both LPS forms are found in wild-type bacteria. They consist of a lipid moiety, lipid A, which comprises a (phosphorylated) disaccharide of glucosamine or 2,3-diamino-2,3-dideoxy-D-glucose that is acylated by ester- and amide-bound fatty acids, and of the core region (4) which is covalently linked to lipid A. Only in S-form LPS is this core region substituted further, that is, by the O-specific polysaccharide (O-antigen). Because mutants that are not able to synthesize a minimal core structure are not viable, the core region and lipid A represent the common structural principle of all LPS.