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 1 H and 13 C 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-Gal pNAcA-(1→3)- α- d-Qui pNAc4NHb-(1→2)- β- d-Qui p3NHb-(1→2)- α- l-Rha p-(1→.