Crystal state and solution conformation of the B blood group trisaccharidealpha-L-Fucp-(1 -> 2)-[alpha-D-Galp]-(1 -> 3)]-beta-D-Galp-OCN3

The crystal structure of the human B blood group related trisaccharide alph a-L-Fucp-(1-->2)-[alpha-D-Galp]-(1-->3)-beta-D-Galp-OCH3 (1) has been deter mined. The solution structure of 1 was studied by two-dimensional NMR techn iques at 600 MHz in D2O solution and the conformational properties were ana lyzed in terms of the torsional angles phi(H) and psi(H), derived from (3)J (CH) coupling constants, and 10 inter-residue proton-proton distances. (3)J (CH) could be accurately measured by a recently introduced two-dimensional heteronuclear correlation experiment (EXSIDE). The nuclear Overhauser enhan cement-derived distances and the calculated torsion angles were compared wi th the same information available from the crystal structure. The agreement is excellent, indicating that the trisaccharide adopts a restricted confor mation in solution, which was also predicted by the Hard Sphere Exo-Anomeri c forcefield. The data of 1 are complemented by NMR studies of the closely related alpha-L-Fucp-(1--->2)-[6-deoxy-alpha-D-Galp]-(1-->3)-beta-D-GalpO-( CH2)(7)CH3 trisaccharide (2).