Structural studies of the capsular polysaccharide from Streptococcus pneumoniae Type 12F

The capsular polysaccharide from Streptococcus pneumoniae type 12F is composed of D -glucosyl, D -galactosyl, 2-acetamido-2-deoxy- D -galactosyl, 2-acetamido-2,6-dideoxy- L -galactosyl, and 2-acetamido-2-deoxy- D -mannuronic acid residues in the proportions 2:1:1:1:1. The main structural evidence was adduced from nmr spectroscopy, methylation analysis, and specific degradations whereby it could be concluded that the polysaccharide is composed of hexasaccharide repeating-units having the structure: