Oligosaccharides Related To Tumor-associate Antigens .2. Conformational-analysis of the Trisaccharide Alpha-L-fucp-(1-2)-beta-D-galp-(1-3)-beta-D-galpNAc, Epitope Structure Recognized By the Mbr1 Antibody

The conformational space of the trisaccharide alpha-L-Fuc-(1 --> 2)-beta-D-Gal-(1 --> 3)-beta-D-GalNAc-1-OPr (2) and of its component disaccharide moieties alpha-L-Fuc-(1 --> 2)-beta-D-Gal-1-OMe (3) and beta-D-Gal-(1 --> 3)-beta-D-GalNAc-1-OPr (4) was investigated with the aid of molecular-mechanics energy minimizations and molecular-dynamics simulations. These calculations suggested the occurrence of two conformations for each compound characterized by different phi and psi glycosidic angles. However, H-1-NMR investigation of D2O solutions of 2-4 indicated a sure preference for one of the two conformers with a contribution of the other one ranging from negligible to low.