Structural Studies on a New Water-absorbing Polysaccharide from the Family Oxalobacteraceae

The chemical structure of a new water-absorbing polysaccharide (WAP), which was isolated from a liquid culture of bacterium belonging to the family Oxalobacteraceae, was analyzed by fragmentation analysis and methylation techniques. Mild acid hydrolysis of WAP gave six di-, four tri-, two tetra-, two penta-, and one hexasaccharides composed of mannose, glucose and/or galactose. These structures were elucidated by extensive 2D NMR spectroscopic analyses. The structure of the WAP has been proposed to have a new heptasaccharide as a repeating unit, →4)-β-D-Glcp-(1→4)-β-D-Manp-(1→4)-β-D-Glcp-(1→4)-[β-D-Galp-(1→3)-β-D-Glcp-(1→3)-β-D-Galp-(1→3)]-β-D-Galp-(1→.