Structural studies of the O-antigenic polysaccharide from Plesiomonas shigelloides strain AM36565

The structure of the repeating unit of the O-antigenic polysaccharide from Plesiomonas shigelloides strain AM36565 has been determined. Component analysis and H-1 and C-13 NMR spectroscopy experiments were employed to elucidate the structure. Inter-residue correlations were determined by H-1,C-13 heteronuclear multiple-bond correlation, H-1-H-1-NOESY, and H-1,C-13-HSQC-H-1,H-1-NOESY experiments. The O-antigen polysaccharide is composed of repeating units with the following structure: -> 3)-alpha-L-Rhap-(1 -> 2)-alpha-L-Rhap-(1 -> 4)[(beta-D-GalpNAc-(1 -> 3)]-alpha-D-GlcpNAc-(1 ->, in which the monosaccharide side-chain substitutes the backbone in half of the repeating units. A matrix-assisted laser desorption/ionization mass spectrometry experiment suggested that the polysaccharide consists of two regions, one with tetrasaccharide repeating units and one with trisaccharide repeating units. (C) 2011 Elsevier Ltd. All rights reserved.