Identification of N epsilon-[(R)-1-carboxyethyl]-L-lysine in, and the complete structure of, the repeating unit of the O-specific polysaccharide of Providencia alcalifaciens O23.

N epsilon-[(R)-1-Carboxyethyl]-L-lysine was released by acid hydrolysis from the O-specific polysaccharide of Providencia alcalifaciens O23 and identified by 1H and 13C NMR spectroscopy, GLC-MS after conversion to a di-N-acetylated dimethyl ester, and by comparison with the authentic sample. Solvolysis of the polysaccharide with anhydrous HF resulted in an amide of D-glucuronic acid with N epsilon-[(R)-1-carboxyethyl]-L-lysine. These and published data allowed the determination of the full structure of the repeating unit of the O-specific polysaccharide.