The synthesis and conformational properties of the diastereoisomeric β D Gal(1→4)β D GlcNAc(1→6)6-C-CH3- D -Gal trisaccharides

The trisaccharide βDGal(1 → 4)βDGlcNAc(1 → 6)DGal was known to be bound strongly by the so-called anti-I Ma monoclonal antibody. In order to help assess the conformation about the 1 → 6 glycosidic linkage that is accepted by the antibody combining site, the conformationally well-defined βDGal(1 → 4)βDGlcNAc(1 → 6) derivatives of 7-deoxy-L-glycero-D-galacto-heptopyranose and 7-deoxy-D-glycero-D-galacto-heptopyranose were synthesized. The conformational preferences for these trisaccharides were established by 1H nmr spectroscopy and rationalized by computer-assisted molecular modelling.