[Antigenic polysaccharides of bacteria. 26. Structure of O-specific polysaccharides from Pseudomonas cerasi 467 and Pseudomonas syringae pv. syringae strains 218 and P-55 belonging to serogroups II and III].

Serologically active O-specific polysaccharides were obtained on mild acid hydrolysis of lipopolysaccharides from Pseudomonas cerasi 467 and Pseudomonas syringae pv. syringae strains 218 and P-55. On the basis of 1H- and 13C-NMR analysis, it was concluded that the P. cerasi polysaccharide has the following structure: ----3)-alpha-D-Rhap-(1----3)-alpha-D-Rhap-(1----2)-alpha-D-+ ++Rhap-(1---- which is identical to that of O-specific polysaccharide from P. syringae pv. morsprunorum C28 (Smith A. R. W. et al. Eur. J. Biochem., 1985, V. 149, No 1, p. 73-78). The polysaccharides from P. syringae pv. syringae strains possess the same backbone but differ by the presence of D-fucose as monosaccharide branches. Methylation and 1H- and 13C-NMR analysis revealed the following structure of these polysaccharides: (Formula: see text). The degree of substitution of the backbone trisaccharide units by the fucofuranose residues is about 35% for the strain 218 and about 85% for the strain P-55.