COMPUTER-ASSISTED STRUCTURAL-ANALYSIS OF THE ESCHERICHIA-COLI O1A, O1B, AND O1C SPECIFIC POLYSACCHARIDES

A computer evaluation of C-13-NMR data for the title polysaccharides b ased on the monosaccharide and methylation analysis data led to the st ructure of the repeating unit of the O1A polysaccharide as well as to several probable structures of the O1C polysaccharide, of which the co rrect one was inferred by means of a single NOE experiment. The analys is of the spectrum of the O1B polysaccharide was unsuccessful, due to the presence in its structure of the fragment alpha-L-Rha-(1 --> 2)-al pha-D-Gal-(1 --> 3)-D-GlcNAc with the terminal (1 --> 2)-linkage, whos e spectral data could not be calculated by additive schemes using only glycosylation effects. However in reevaluation of the O1B spectral da ta by taking in to account the deviations from additivities of the che mical shifts values in spectra of the related trisaccharides, to revea l the most probable structure of the O1B's repeating unit. [GRAPHICS]