Pyruvated galactose and oligosaccharides from Erwinia chrysanthemi Ech6 extracellular polysaccharide

The acidic extracellular polysaccharide of Ech6 was depolymerized by fuming HCl. The pyruvated sugars were isolated and characterized by methods that included a combination of low-pressure gel-filtration and high-pH anion-exchange chromatographies, methylation linkage analyses, mass (GC-MS and MALDI-TOF MS) and 1H NMR (1D and 2D) spectroscopies. The following pyruvated sugars were obtained: 4,6-O-(1-carboxyethylidene)-D-Galp; 4,6-O-(1-carboxyethylidene)- alpha-D-Galp-(1-->4)-beta-D-GlcAp-(1-->3)-D-Galp; 4,6-O-(1-carboxyethylidene)-alpha-D-Galp-(1-->4)-alpha-D-GlcAp- (1-->3)-alpha-D-Galp-(1-->3)-L-Fucp; 4,6-O-(1-carboxyethylidene)-alpha-D-Galp-(1-->4)-beta-D-GlcAp-(1-->3) -alpha-D-Galp-(1-->3)-L-beta-D-Glcp-(1-->4)]-Fucp. These oligosaccharides present potential haptenes for the development of specific antibodies and confirm the partial structure proposed previously for the extracellular polysaccharide from Erwinia chrysanthemi Ech6 Yang, B. Y.; Gray, J. S. S.; Montgomery, R. Int. J. Biol. Macromol., 1994, 16, 306-312].