Determination of solution conformation of allergenically active pentasaccharitol obtained from sea squirt antigen

Pentasaccharitol, GalNAc beta1-4(GalNAc alpha1-2Fuc alpha1-3)GlcNAc beta 13GalNAc-ol, termed HPG-beta2-N5a, is an allergenically active O-linked oligosaccharitol derived from a sea squirt H-antigen. Concerning the interaction between the allergen and specific IgE, an analysis of the solution conformation of the saccharitol was carried out. H-1 and C-13 NMR assignments for the pentasaccharitol were obtained using 1D-HOHAHA, TOCSY, DEPT135, HSQC and HMBC techniques. The solution conformation was determined using a combination of 2D-NMR ROESY data and distance geometry (DG) calculations in dihedral angle space with the DADAS 90 program. Two conformers, family A (FamA) and family B (FamB), that satisfied almost all the NOE constraints were obtained, and supplemental MD calculations revealed that FamA was in conformational equilibrium whereas FamB was rather flexible. The molecule of HPG-beta2-N5a had a layered and not a linear conformation. Copyright (C) 2001 John Wiley & Sons, Ltd.