Group D Types 1 and 26 cell walls and the corresponding type-specific carbohydrates, extracted from the walls by various means, contain rhamnose, glucose, galactose, N-acetylglucosamine, and N-acetylgalactosamine. Mucopeptide elements are also present in the walls and in enzymatically-extracted carbohydrates. Types 1 and 26 carbohydrates extracted by formamide contain no mucopeptide, but the serologic reactivity of Type 1 antigen is destroyed by this procedure. The Type 1 antigen was successfully extracted, however, by a new technique involving autolysis of cell walls at pH 6.2. The type carbohydrate prepared by this procedure has chemical and serological similarities to the antigens prepared by the S. albus enzyme and the lysozyme methods.
Quantitative precipitin inhibition studies with Type 1 antigen and antibody indicate that D-glucose and N-acetylglucosamine may be components of the antigenic determinant. The terminal residue is probably bound by an ß-glycosidic bond to the subterminal sugar.
Similar studies with the Type 26 carbohydrate have not revealed any of the chemical features of the antigenic determinant.