NMR of Synthetic Saccharides Related to E. coli O-148 and B. Burgdorferi

A comprehensive manuscript has been written on the organic synthesis of oligosaccharide components of the OSP of E. coli O148, including saccharides containing 4, 6, 7, 8, 10, 11, and 12 residues. Protein conjugates of these saccharides with bovine serum albumin and recombinant diphtheria toxoid have also been prepared, and their anti-LPS IgG immunochemical values measured and compared with those of the corresponding diphtheria toxoid conjugates of oligosaccharide components of the OSP of Shigella dysenteriae type 1 containing 8, 10, 11, 12, or 13 saccharide residues. <P> The manuscript includes seven tables of data on the H-1 chemical shifts, C-13 chemical shifts, H-1/H-1 coupling constants, and 1J C-1,H-1 heteronuclear coupling constants of the 4-mer, 8-mer, and 12-mer5-methoxycarbonylpentyl glycosides , and a two-part Figure indicating the similarity of the 1H-coupled HSQC NMR spectra of the 8-mer and 12-mer glycosides, but also how these oligomers may be distinguished by the intensities of the cross-peaks in the spectra. In the course of validating the structures of synthetic BBGL-2 variants by 1D and 2D NMR methods, we have now made detailed H-1 and C-13 NMR assignments for four of these structures; namely, 1,2-di-O-oleoyl-, 1-O-oleoyl-2-O-palmitoyl-, 1-O-palmitoyl-2-O-oleoyl-, and 1,2-O-palmitoyl-3-O-alpha-D-galactopyranosyl-sn-glycerols. Interpretation of the C-13=O chemical shifts of the four galactosyl diglycerides has led to a set of rules that describe the dependence of these C-13 shifts on fatty acid type, and substituent position on the glycerol moiety. The rules are useful for NMR analysis of the mixtures of products that result from acylation reactions of imperfect regiospecificity. The NMR data for the four diglyceride analogs have been published as part of a detailed report on the synthesis and antigenicity of BBGL-2 analogs.