HIGH-RESOLUTION SOLID-STATE-C-13 CP/MAS NMR-STUDY OF SCLEROGLUCAN HYDRATION

Scleroglucan is a branched polysaccharide, soluble in water. Solid-state and solution C-13 NMR were used to follow the fixation of water molecules on anhydrous scleroglucan and the evolution of the scleroglucan-water complex from the solid state to the gel and solution state. Determination of both chemical shift values and relaxation times (T(CH)D, T1rhoH and T1C) for anhydrous and hydrated scleroglucans permit the observation of a transition between the two forms. The fixation of water leads to an increase in the solid-state order, in the form of a triple-helix association, and at the same time an increase in the interchain distance and in the molecular motion. The gel state obtained for a water-scleroglucan composition of 90:10 is characterized by an important macromolecular rigidity which implies the use of the solid-state NMR techniques. Solution C-13 NMR can be utilized to characterize the primary structure and the triple-helix random-coil conformational transition.