Somatic antigens of pseudomonads: Structure of the O-specific polysaccharide of Pseudomonas fluorescens biovar B, strain IMV 247

The O-specific polysaccharide of Pseudomonas fluorescens biovar B, strain IMV 247, was studied by acid hydrolysis, GLC–MS and 1H and 13C NMR spectroscopy, including 1D and 2D NOE, 2D hybrid TOCSY and ROESY (TORO), and 2D H-detected heteronuclear multiple-bond correlation (HMBC) experiments. The polysaccharide was found to contain l-rhamnose, 3,6-dideoxy-3-[(S)-3-hydroxybutyramido]-d-glucose (d-Qui3NHb), 2-acetamido-2,4,6-trideoxy-4-[(S)-3-hydroxybutyramido-d-glucose (d-QuiNAc4NHb) and 2-acetamido-2-deoxy-d-galacturonic acid (d-GalNAcA). Partial acid hydrolysis of the polysaccharide resulted in a non-reducing GalNAcA→QuiNAc4NHb disaccharide with the 3-hydroxybutyryl group glycosylated intramolecularly by the QuiN4N residue. The following structure of the tetrasaccharide repeating unit of the polysaccharide was established: →4)-α-d-GalpNAcA-(1→3)-α-d-QuipNAc4NHb-(1→2)-β-d-Quip3NHb-(1→2)-α-l-Rhap-(1→.