Structure of the O-polysaccharide of Providencia alcalifaciens O35 containing an N-[(S)-1-carboxyethyl]-l-alanine (alanopine) derivative of 4-amino-4,6-dideoxyglucose

Abstract

The O-polysaccharide of Providencia alcalifaciens O35 was studied by sugar and methylation analyses along with 1H and 13C NMR spectroscopy, including 2D 1H,13C HMBC, and NOESY experiments in D2O and, to detect correlations for NH protons, in a 9:1 H2O/D2O mixture. A unique N-(1-carboxyethyl)alanine (alanopine, Alo) derivative of 4-amino-4,6-dideoxyglucose (Qui4N) was identified as the polysaccharide component. Alanopine was isolated by solvolysis of the polysaccharide with triflic acid followed by acid hydrolysis, and its (2S,4S)-configuration was determined by the specific optical rotation. The following structure of the O-polysaccharide was established (the d configuration of Qui4N was ascribed tentatively): [Display omitted]