Abstract
Rabbit antibodies against pneumococcus capsular polysaccharides of Types II, III, VI, VII, and XII were isolated from type-specific antisera by precipitation with homologous antigen and hydrolyzed with either subtilisin, chymotrypsin or trypsin. Purified antibodies were also hydrolyzed with papain; the two polypeptides with active antibody sites and the crystallizable polypeptide were separated, studied in the ultracentrifuge and hydrolyzed with either subtilisin or chymotrypsin. The resulting peptides were separated on filter paper by electrophoresis and chromatography.