The type-specific substance from Pneumococcus type 29.

1. A pentasaccharide, corresponding to the dephosphorylated repeating unit of the specific substance, S.29, from Pneumococcus type 29, was obtained by hydrolysis with alkali followed by enzymic dephosphorylation. 2. The pentasaccharide was shown to be O-2-acetamido-2-deoxy-beta-d-galactopyranosyl-(1-->6)-O-beta-d-galactofuranosyl-(1-->3)-O-beta-d-galactopyranosyl-(1-->6)-O-beta-d-galactofuranosyl-(1-->1)-ribitol. 3. The phosphodiester linkages in S.29 join the hydroxyl group at position 5 of ribitol and the hydroxyl group at position 3 or 4 of a 2-acetamido-2-deoxy-d-galactose residue in the next repeating unit. 4. A partial structure for S.29 was deduced from these experiments.