Structure of the type 38 Streptococcus pneumoniae capsular polysaccharide.
Li X, Puvanesarajah V, Berti F
Carbohydrate research •
Streptococcus pneumoniae is one of the globally important encapsulated human pathogens and more than 100 different serotypes have been identified. Despite very extensive genetic and immune-serological studies, the capsular polysaccharide repeating unit structure of several serotypes has not been determined yet, including the type 38 (type 38 in Danish nomenclature; type 71 in US nomenclature). Physicochemical data revealed that type 38 polysaccharide is composed of a pentasaccharide repeat unit →3)-[β-D-Galf(1 → 2)]-β-D-GalpA6(L-Ser)-(1 → 3)-α-D-GlcpNAc-(1 → 3)-α-D-Sugp-(1 → 4)-α-D-Galp(2OAc)-(1 → . The polysaccharide is O-acetylated at position C of the α-Gal residue at approximately (68-87 %) of the repeat units.