Conformational studies of blood group A and blood group B oligosaccharides using NMR residual dipolar couplings

• Published in: Carbohydrate research Vol. 337; no. 10; pp. 905 - 915
• Main Authors: Azurmendi, Hugo F., Bush, C.Allen
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 13.05.2002
• Subjects: ABO Blood-Group System - chemistry; Animals; Blood group; Carbohydrate Conformation; Magnetic Resonance Spectroscopy; Models, Molecular; Monte Carlo Method; NMR, residual dipolar coupling; Oligosaccharide conformation; Oligosaccharides - chemistry; Solutions; Swine - blood; NMR, residual dipolar coupling; Blood group; Oligosaccharide conformation
• ISSN: 0008-6215; 1873-426X
• DOI: 10.1016/S0008-6215(02)00070-8

The conformations of two synthetic trisaccharides of blood group A and B (α- l-Fuc p-(1→2)-[α- d-Gal pNAc-(1→3)]-α- d-Gal p and α- l-Fuc p-(1→2)-[α- d-Gal p-(1→3)]-α- d-Gal p, respectively) and of a type A tetrasaccharide alditol, Fuc p-(1→2)-[α- d-Gal pNAc-(1→3)]-β- d-Gal p-(1→3)-GalNAc-ol, were studied by NMR measurements of one-bond CH residual dipolar couplings in partially oriented liquid crystal solutions. The conformations of the three oligosaccharides were analyzed by generating thousands of structures using a Monte–Carlo method. Two different strategies were applied to calculate theoretical dipolar couplings for these structures. In the first method, the orientation of the molecule was calculated from the optimal fit of the molecular model to the experimental data, while in the second method the orientation tensor was calculated directly from the moment of inertia of the molecular model. Both methods of analysis give similar results but with slightly better agreement with experiment for the former one. The analysis of the results implies a single unique conformation for both blood group epitopes in solution in disagreement with theoretical models suggesting the existence of two conformers in solution. The conformations of two synthetic trisaccharides of blood groups A and B were studied by NMR measurements of one-bond CH residual dipolar couplings in partially oriented liquid crystal solutions. The analysis implies a single unique conformation for both blood group epitopes, which is in disagreement with theoretical models.