THE STRUCTURE OF THE LIPID A-CORE REGION OF THE LIPOPOLYSACCHARIDES FROM VIBRIO-CHOLERAE O1 SMOOTH STRAIN 569B (INABA) AND ROUGH MUTANT STRAIN 95R (OGAWA)

The lipopolysaccharides (LPS) from Vibrio cholerae 95R, a rough mutant strain of O1 V. cholerae 162 (Ogawa), and from smooth O1 V. cholerae 569B (Inaba) were de-O-acylated. In each case, one part of the products was treated with 48% aqueous HF which removed the phosphoryl and fructose residues, then reduced, de-N-acylated, and N-acetylated. Another part was de-N-acylated by treatment with hot KOH. The products of both degradation pathways were separated by high-performance anion-exchange chromatography. The major dephosphorylated and defructosylated product 1 was obtained in pure form, whereas the minor products 2 and 3 were eluted as a mixture, as were, from the second degradation, the phosphorylated oligosaccharides 4 (major product) and 5 (minor product). No phosphorylated component corresponding to oligosaccharide 3 could be identified by NMR spectroscopy in the latter mixture. The following structures of oligosaccharides 1-5 were established on the basis of monosaccharide and methylation analyses, Smith degradation, and H-1- and C-13-NMR investigations (correlated, total correlated, NOE and heteronuclear correlation spectroscopy; all sugars are present as alpha-D-pyranoses except where indicated otherwise; Hep, L-glycero-D-manno-heptose; Kdo, 3-deoxy-D-manno-2-octulosonic acid). [GRAPHICS] In the untreated lipopolysaccharide, the amino group of the non-reducing terminal glucosamine residue is not substituted.