HYDRATION STUDIES OF CARBOHYDRATES .4. NMR-STUDIES OF CARBOHYDRATE HYDRATION

Measurement of water oxygen-17 relaxation times has been used to provi de information about the hydration behaviour of some carbohydrates in aqueous solution. While a solvent water molecule is 'bound' to the sol ute, its reduced rotation is reflected in the solvent n.m.r. relaxatio n. The experimental data are consistent with a fast-exchange two-state model of carbohydrate hydration. Such a model allows calculation of t he activation energies for the molecular processes involved in spin re laxation of bound water. The activation energies provide information a bout the specific hydration properties of individual sugars. Dynamic h ydration numbers of five aldohexoses and two methyl glucopyranosides h ave been determined. These hydration numbers correlate well with hydra tion parameters derived from a number of techniques. Overall, the resu lts provide additional support for a stereospecific model of monosacch aride hydration.