Structure of the O-specific polysaccharide of Providencia rustigianii O14 containing N(epsilon)-[(S)-1-carboxyethyl]-N(alpha)-(D-galacturonoyl)-L-lysine.

The O-specific polysaccharide of Providencia rustigianii O14 was obtained by mild acid degradation of the LPS and studied by chemical methods and NMR spectroscopy, including 2D 1H,(1)H COSY, TOCSY, NOESY, and 1H,(13)C HSQC experiments. The polysaccharide was found to contain N (epsilon)-[(S)-1-carboxyethyl]-N(alpha)-(D-galacturonoyl)-L-lysine ('alaninolysine', 2S,8S-AlaLys). The amino acid component was isolated by acid hydrolysis and identified by 13C NMR spectroscopy and specific optical rotation, using synthetic diastereomers for comparison. The following structure of the trisaccharide repeating unit of the polysaccharide was established:Anti-P. rustigianii O14 serum was found to cross-react with O-specific polysaccharides of Providencia and Proteus strains that contains amides of uronic acid with N(epsilon)-[(R)-1-carboxyethyl]-L-lysine and L-lysine.