Structural studies on the lipopolysaccharide from a rough strain of Ochrobactrum anthropi containing a 2,3-diamino-2,3-dideoxy- d-glucose disaccharide lipid A backbone

Abstract

A degradation protocol using de- O-acylation and subsequent alkaline de- N-acylation was applied to the lipopolysaccharide of Ochrobactrum anthropi rough strain LMG 3301. Three main oligosaccharide bisphosphates containing core–lipid A backbone structures were obtained after fractionation by anion-exchange HPLC. Using 1 H and 13 C NMR spectroscopy, including two-dimensional COSY, TOCSY, and NOE spectroscopy (ROESY and NOESY), the following structures were established: where Kdo is 3-deoxy- d- manno-octulosonic acid, d-GlcN3N is 2,3-diamino-2,3-dideoxy- d-glucose and R is H or α- d-Gal pA or 4-deoxy- β- l- threo-hex-4-enopyranuronic acid, the latter sugar being derived from α- d-Gal pA by β-elimination of a substituent attached to O-4. This is the first report on the isolation from a lipopolysaccharide of an oligosaccharide containing GlcN3N in the lipid A backbone [ β- d-Glc pN3N4 P-(1→6)- α- d-Glc pN3N1 P]. Sugar and methylation analysis confirmed the presence of the GalA→Kdo disaccharide and non-stoichiometric substitution of GalA. It is suggested that Glc is the substituent at O-4 in GalA and that in the non-degraded lipopolysaccharide the amino group of GlcN is not acylated.