Structure of the O-polysaccharide of Erwinia carotovora ssp atroseptica GSPB 9205 containing a new higher branched monosaccharide

An O-polysaccharide was prepared by mild acid hydrolysis of a lipopolysaccharide of Erwinia carotovora ssp. atroseptica GSPB 9205 and was found to contain a new higher branched monosaccharide, viz., 3,6,8-trideoxy-4-C-(R-1-hydroxyethyl)-D-gulo-octose, which we called erwiniose. The structure of the pentasaccharide repeating unit of the O-polysaccharide was established by monosaccharide analysis, including the determination of absolute configurations, methylation analysis, O-deacetylation, Smith degradation, and one- and two-dimensional NMR spectroscopy. The configuration of erwiniose was determined based on the coupling constants of vicinal protons combined with the nuclear Overhauser effect data and the results of periodate oxidation of the polysaccharide followed by reduction of the resultant 4-keto sugar (the C(1)-C(4)-C(1')-C(2') fragment) to give 3,6-dideoxy-D-ribo-hexose (paratose) and oxidation of 3-hydroxybutyraldehyde (the C(5)-C(8) fragment) to give R-3-hydroxybutyric acid.