The structure of the O-specific polysaccharide chain of the Shewanella algae BrY lipopolysaccharide

An acidic O-specific polysaccharide was obtained by mild acid degradation of the Shewanella algae strain BrY lipopolysaccharide and was found to contain l-rhamnose, 2-acetamido-4-[d-3-hydroxybutyramido)]-2,4,6-trideoxy-d-glucose (d-BacNAc4NHbu), and 2-amino-2,6-dideoxy-l-galactose, N-acylated by the 4-carboxyl group of l-malic acid (l-malyl-(4→2)-α-l-FucN) in the ratio 2:1:1. 1H and 13C NMR spectroscopy was applied to the intact polysaccharide, and the following structure of the repeating unit was established:-3)-α-d-BacNAc4NHbu-(1→3)-α-l-Rha-(1→2)-α-l-Rha-(1→2)-l-malyl-(4→2)-α-l-FucN-(1-The repeating unit includes linkage via the residue of malic acid, reported here for the first time as a component of bacterial polysaccharides.