New structure for the O-polysaccharide of Providencia alcalifaciens O27 and revised structure for the O-polysaccharide of Providencia stuartii O43

摘要

The O-polysaccharide was obtained by mild acid degradation of the Upopolysaccharide from Providencia alcalifaciens O27 and studied by sugar and methylation analyses along with 1H and 13C NMR spectroscopy,including 2D 1H,1H COSY,TOCSY,ROESY,H-detected 1H,13C HSQC,and HMBC experiments.It was found that the polysaccharide is built up of linear partially O-acetylated tetrasaccharide repeating units and has the following structure: OAc (approx 70%)-6 [4)-beta-D-Glcp-(l->3)-beta-D-GalpNAc-(l->2)-alpha-D-Quip4NFo-(1->4)-alpha-D-GlcpA-(1->]n where Qui4NFo stands for 4-formamido-4,6-dideoxyglucose (4-formamido-4-deoxyquinovose). The O-polysaccharide structure of Providencia stuartii O43 established earlier was revised with respect to the configuration of the constituent 4-amino-4,6-dideoxyhexose (from Rha4N to Qui4N).