Full assignment of the 1H and 13C spectra and revision of the O-acetylation site of the capsular polysaccharide of Streptococcus pneumoniae Type 33F, a component of the current pneumococcal polysaccharide vaccine.

The structure of the capsular polysaccharide from Streptococcus pneumoniae Type 33F was originally determined by a combination of chemical methods and limited use of NMR spectroscopy [Can. J. Biochem. Cell Biol.1984, 62, 666-677]. We report full 1H and 13C assignments and confirm the structure of the saccharide repeat unit, but find that the site of O-acetylation is O-2 of the -->5)-beta-D-Galf, rather than the -->3)-beta-D-Galf residue. We find that a slightly higher percentage of the repeat units are O-acetylated: [carbohydrate: see text].