α‐2→4‐Interlinked 3‐deoxy‐ d ‐ manno ‐octulosonic acid disaccharide

After mild acid hydrolysis, a disaccharide of 3‐deoxy‐ d ‐ manno ‐octulosonic acid (dOclA) was obtained from Re‐mutant lipopolysaccharide of Salmonella minnesota, Salmonella godesberg, Proteus mirabilis , and Escherichia coli , and from the lipopolysaccharide of an S. minnesota Rb 2 mutant. Combined gas‐liquid chromatography/ mass spectrometry of the reduced and permethylated derivatives indicated that the disaccharide is interlinked by a 2 4‐glycosidic bond in all lipopolysaccharides tested. In addition, it was shown by gas‐liquid chromatography of appropriate synthetic standards and a previously characterized α2 4‐linked dOclA disaccharide (derived from lipopolysaccharide of S. godesberg ) that the non‐reducing dOclA residue possesses the α configuration. In the case of lipopolysaccharide of S. minnesota Rb 2 mutant, this result, together with earlier findings, suggests that it contains a linear dOclA trisaccharide of the sequence dOclA (α2–4)dOclA(α2–4)dOclA. The results show that a dOclA (α2–4)dOclA disaccharide represents a common architectural principle in enterobacterial lipopolysaccharides.