Crystal state and solution conformation of the B blood group trisaccharide α-L-Fucp-(1→2)-[α-D-Galp]-(1→3)]-β-D-Galp-OCH3

Abstract

The crystal structure of the human B blood group related trisaccharide α-L-Fucp-(1→2)-[α-D-Galp]-(1→3)-β-DGalp-OCH3 (1) has been determined The solution structure of 1 was studied by two-dimensional NMR techniques at 600 MHz in D2O solution and the conformational properties were analyzed in terms of the torsional angles Φ(H) and ψ(H), derived from 3J(CH) coupling constants, and 10 inter-residue proton-proton distances. 3J(CH) could be accurately measured by a recently introduced two-dimensional heteronuclear correlation experiment (EXSIDE). The nuclear Overhauser enhancement-derived distances and the calculated torsion angles were compared with the same information available from the crystal structure. The agreement is excellent, indicating that the trisaccharide adopts a restricted conformation in solution, which was also predicted by the Hard Sphere Exo-Anomeric forcefield The data of 1 are complemented by NMR studies of the closely related α-L- Fucp-(1→2)-[6-deoxy-a-D-Galp]-(1→3)-β-DGalpO-(CH2)7CH3 trisaccharide (2).