title: Degradation of a pneumococcal type-specific polysaccharide with exposure of group-specificity.
abstract: Pyruvic acid is an immunological determinant of the quite rigorously type-specific capsular polysaccharide of pneumococcal type IV (S IV). Removal of pyruvic acid by mild hydrolysis converts the capsular polysaccharide of type IV into an analog of the pneumococcal group-specific C-substance. Depyruvylated S IV resembles C-substance so closely immunologically that it not only precipitates a high proportion of the anti-C in antipneumococcal sera, regardless of their immunological types, but also, like C, precipitates human C-reactive protein in the presence of calcium ions. Apparently, the removal of pyruvic acid ketal rings from adjacent sugars unmasks N-acetylgalactosamine residues which must be linked and spaced much as are those in C-substance. Groupings reactive with suitably linked N-acetylgalactosamine, therefore, appear to be located on the surfaces of molecules of human C-reactive protein.
mesh_terms: D000937:Antigen-Antibody Reactions; D002097:C-Reactive Protein; D002118:Calcium; D003429:Cross Reactions; D005690:Galactose; D006595:Hexosamines; D006801:Humans; D011135:Polysaccharides, Bacterial; D011773:Pyruvates; D013296:Streptococcus pneumoniae
chemical_list: D006595:Hexosamines; D011135:Polysaccharides, Bacterial; D011773:Pyruvates; D002097:C-Reactive Protein; D002118:Calcium; D005690:Galactose