Structural analysis of the O-specific polysaccharide from the lipopolysaccharide of Aeromonas veronii bv. sobria strain K49

The O-specific polysaccharide obtained by mild-acid degradation of the lipopolysaccharide from Aeromonas veronii bv. sobria strain K49 was studied by sugar and methylation analyses along with H-1 and C-13 NMR spectroscopy. The sequence of the sugar residues was determined using H-1,H-1 NOESY and H-1, C-13 HMBC experiments. The O-specific polysaccharide was found to be a high molecular mass polysaccharide composed of repeating units of the structure: -> 2)-beta-D-Quip3NAc-(1 -> 3)-alpha-L-Rhap-(1 -> 3)-alpha-L-Rhap-(1 -> 2)-alpha-L-Rhap-(1 -> 3)-alpha-D-FucpNAc-(1 -> ESI MS confirmed the pentasaccharide structure of the repeating unit, as the molecular mass peaks seen in the spectrum differed by 812.34 u, a value corresponding to the calculated molecular mass of the O-unit. (C) 2012 Elsevier Ltd. All rights reserved.