Empirical 13C-n.m.r.-correlations between the Escherichia coli K 13 and LP 1092 capsular polysaccharides and model oligosaccharides containing D-ribose and 3-deoxy-D-manno-2-octulosonic acid.

The proton-decoupled, Fourier-transform, 13C-n.m.r. spectra of the two anomeric sodium (methyl 3-deoxy-7-O-beta-D-ribofuranosyl-alpha- and beta-D-manno-2-octulopyranosid)onates, of the two anomeric sodium [methyl 3-deoxy-7-O-(2-O-beta-D-ribofuranosyl-beta-D-ribofuranosyl)-alpha- or -beta-D-manno-2-octulopyranosid]onates, and of methyl 2-O-beta-D-ribofuranosyl-beta-D-ribofuranoside have been recorded. The constitutions of these compounds correspond to repeating units and partial structures of the capsular polysaccharides from Escherichia coli K 13, K 20, K 23, and LP 1092 strains. The 13C-n.m.r.-line patterns of these oligosaccharide derivatives and the corresponding polysaccharides show striking differences dependent upon the anomeric configurations of the KDO residues. These differences may be used for the identification, by visual or computer-assisted pattern analysis, of the anomeric configurations of KDO-residues in oligo- or poly-saccharides. Thus, it was confirmed that the KDO residues in the K 13, K 20, and K 23 polysaccharides have the beta anomeric configuration, whereas those in the LP 1092 polysaccharide have the alpha anomeric configuration.