NMR study on the hydroxy protons of the Lewis X and Lewis Y oligosaccharides.

The 1H NMR chemical shifts and NOEs of hydroxy protons in Lewis X trisaccharide, beta-D-Galp-(1-->4)[alpha-L-Fucp-(1-->3)]-beta-D-GlcpNAc, and Lewis Y tetrasaccharide, alpha-L-Fucp-(1-->2)-beta-D-Galp-(1-->4)[alpha-L-Fucp-(1-->3)]-beta-D-GlcpNAc, were obtained for 85% H2O/15% (CD3)2CO solutions. The OH-4 signal of Galp in Lewis X and OH-3, OH-4 signals of Galp, and OH-2 signal of Fucp linked to Galp in Lewis Y had chemical shifts which indicate reduced hydration due to their proximity to the hydrophobic face of the Fucp unit linked to GlcpNAc. The inter-residue NOEs involving the exchangeable NH and OH protons confirmed the stacking interaction between the Fucp linked to the GlcpNAc and the Galp residues in Lewis X and Lewis Y.