The Chemical Structure of the Lipid A Component of Lipopolysaccharides from Chromobacterium violaceum NCTC 9694

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Abstract
The chemical structure of the lipid A component of lipopolysaccharides from C. violaceum NCTC9694 was studied. Sequential treatment of lipopolysaccharide with alkali, acid, sodium borohydride and hydrazine allowed the isolation of a reduced glucosamine disaccharide. According to methylation studies and enzymic analysis with .beta.-N-acetylglucosaminidase [EC 3.2.1.30] the D-glucosamine [GlcN] residues are .beta.(1 .fwdarw. 6) linked. The disaccharide carries 2 phosphate groups, one being linked glycosidically, the other being linked as an ester to the non-reducing glucosamine. Application of a different degradation pathway shows that the ester-bound phosphate group is substituted by a 4-aminoarabinosyl [4-AraN] residue and that the glycosidically linked phosphate [P] group is substituted by a glucosaminyl residue. Neither the amino nor the hydroxyl groups of both these substituents are acylated. This backbone structure is: .**GRAPHIC**. The amino groups of the central glucosamine disaccharide are substituted by D-3-hydroxydodecanoic acid, the hydroxyl groups by dodecanoic, L-2-hydroxydodecanoic and D-3-hydroxydecanoic acid.