Heteronuclear coupling constants of hydroxyl protons in a water solution of oligosaccharides: trehalose and sucrose

Relatively few details are known about the conformational preferences of hy droxyl groups in carbohydrates in water solution, though these would be inf ormative about solvation and H-bonding. We show that highly concentrated so lutions of sucrose and trehalose exhibit surprisingly well-resolved H-1 NMR spectra in a deuterium oxide-water solvent mixture at subzero temperatures . Measurement conditions are suitable to extract nearly all homonuclear and , for the first time, heteronuclear coupling constants of OH groups of carb ohydrates in their natural abundance. For (2.3)J(HO,C) coupling constants n ew, powerful variants of HETLOC and HECADE techniques were applied. The pre sent data do not support the presence of persistent H-bonds in these two cr yogenic disaccharides. (C) 1999 Elsevier Science Ltd. All rights reserved.