Degradation of a Pneumococcal Type-Specific Polysaccharide with Exposure of Group-Specificity*

AUTOR(ES)
RESUMO

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.

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