It is generally acknowledged that information about carbohydrate conformation is important for the understanding of interaction between carbohydrates and other biomolecules, such as proteins.^1–5 The major part of oligosaccharides involved in the interactions are made up of hexopyranoses, and the overall conformation can be described by the rotation of the glycosidic linkages and the bonds to the exocyclic groups,^6,7 e.g., the hydroxymethyl groups and N-Acetyl groups. The conformation of the hydroxymethyl group is of interest for interactions involving the hydroxyl group at this position.^2,8,9 Furthermor, the conformation of the C5-C6 linkage determines the overall shape of oligosaccharides with glycosidic linkages to 06.^10–27 The conformational preferences of the hydroxymethyl group in mono and oligosaccharides have therefore been the subject of several investigations including both experimental and theoretical studies, as will be discussed in the following.

Deamination of LPSs from Klebsiella pneumoniae released O-chain polysaccharides together with a fragment of the core oligosaccharide. The structures of the products from serotypes O1, O2a, O2a,c, O3, O4, O5, and O12 were determined by NMR spectroscopy and chemical methods, identifying the linkage region between the O antigens and the core as well as novel residues at the non-reducing ends of the polysaccharides. All serotypes had an identical linkage between the O chain and core.