Oligosaccharide fragments of the type III group B streptococcal polysaccharide derived from S. pneumoniae type 14 capsular polysaccharide by a chemoenzymatic method

Partial N-deacetylation of the GlcNAc residues in S. pneumoniae type 14 capsular polysaccharide (Pn14-PS) backbone was achieved by treatment with base, and the product was subsequently enzymatically sialylated at the 3-O-positions of the terminal galactose residues. The resultant, partially N-deacetylated type III Group B streptococcus capsular polysaccharide (GBSIII-PS) was subjected to nitrous acid deamination, which resulted in the degradation of GBSIII-PS polysaccharide into oligosaccharides containing increasing numbers of the identical repeating units. The oligosaccharides were then separated by passage through a Superdex 30 column and characterized by ESIMS and NMR spectroscopic analysis.