Immunochemical studies on the O-specific side chains of the heterogeneous lipopolysaccharide from Proteus mirabilis O27.

Chemically and serologically identical O-specific fractions were isolated from two different lipopolysaccharide (LPS) preparations of Proteus mirabilis O27. The release of a labile constituent in mild hydrolysis deprived those fractions of their serological activity. The compound was identified as N-acetyl-D-glucosamine and its terminal position in the molecule was established by methylation analysis. The non-carbohydrate constituent of the specific fractions: lysine and alanine are linked via their amino group. Terminal residues of N-acetylglucosamine, have to be considered as immunodeterminants of Proteus mirabilis O27. The role of other carbohydrate and non-carbohydrate constituents for the serological specificity of P. mirabilis O27 is discussed.