Abstract
Mild hydrazinolysis of Pseudomonas fluorescens strain ATCC 49271 lipopolysaccharide (LPS) followed by strong alkaline degradation and purification by anion-exchange HPLC resulted in two phosphorylated oligosaccharides (1 and 2). On the basis of compositional analysis and 1H, 13C, and 31P NMR spectroscopy, including 2D correlation spectroscopy (COSY), 2D rotating frame NOE spectroscopy (ROESY), and 2D inverse mode H-detected heteronuclear 1H-13C and 1H-31P correlation spectroscopy, the following two structures (1 and 2) could be identified [formula: see text] where Hep is L-glycero-D-manno-heptose, Kdo is 3-deoxy-D-manno-octulosonic acid, Non is 5,7-diamino-3,5,7,9-tetradeoxy-D-glycero-L-galacto-nonulosonic acid, and P is phosphate. Decasaccharide 1 and tridecasaccharide 2 represent an incomplete core and the complete core carrying one O-antigen repeating unit, respectively. Both are attached to the lipid A backbone but, due to their degradation protocol, they lack N- and O-acyl substituents, including N- and O-acetyl groups, the 5-N-acetimidoyl group of Non, the 2-N-alanyl group of GalN, and the 7-O-carbamoyl group of Hep as well as diphosphate, triphosphate, and, probably, some of the monophosphate groups that are present in the intact core oligosaccharide.
