The core structure of the lipopolysaccharide (LPS) isolated from a rough strain of the phytopathogenic bacterium Pseudomonas , GSPB 711, was investigated by sugar and methylation analyses, Fourier transform ion-cyclotron resonance ESI MS, and one- and two-dimensional 1 H-, 13 C- and 31 P-NMR spectroscopy. Strong alkaline deacylation of the LPS resulted in two core-lipid A backbone undecasaccharide pentakisphos-phates in the ratio : 1, which corresponded to outer core glycoforms 1 and 2 terminated with either L-rham-nose or 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo), res-pectively
