Structure of an Acidic Exopolysaccharide of Burkholderia pseudomallei

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Abstract
A recently described water‐soluble exopolysaccharide of Burkholderia pseudomallei recognized by the IgG 1 monoclonal antibody 3015 [Steinmetz, I., Rohde, M. & Brenneke, B. (1995) Infect. Immun. 63, 3959–3965] was isolated by repetitive ethanol‐precipitation steps and by anion‐exchange chromatography. The structure of the polysaccharide was determined by a combination of chemical‐derivatization and mass‐spectrometric techniques (compositional and methylation analysis, GC/MS, and electrospray‐ionization‐MS/MS of reduced and permethylated hydrolytic fragments), and two‐dimensional 1H‐NMR methods (COSY, TOCSY and NOESY) and confirmed by isolation and structural characterization of the depolymerized repeating unit of the polysaccharide. The combined structural data established a linear tetrasaccharide repeating unit consisting of three galactose residues, one bearing a 2‐linked O‐acetyl group, and a 3‐deoxy‐D‐manno‐2‐octulosonic acid residue.