Hydration of glucose and galactose derivatives

The spin-lattice relaxation times, T-1, of (H2O)-O-17 have been measured fo r aqueous solutions of glucose and galactose derivatives, which are substit uents of the 2-OH or 6-OH of these sugars, as a function of the concentrati on at 25 degreesC. The values of the coordination numbers, nl,, have been e stimated on the basis of the water-accessible surface areas (ASA) of the so lute molecules. The rotational correlation times, tau (h)(c), of water mole cules around the solute were estimated and compared with that of pure water , tau (0)(c). All values of the tau (h)(c)/tau (0)(c) for the derivatives w ere smaller than those of the parent sugars, and the value of tau (h)(c)/ta u (0)(c) = 1.26 for glucosamine was the smallest among these derivatives. T he greater the hydration of the parent sugars is, the more the hydration la yer will be disturbed by the substituted groups.