MANIFESTATION OF ANOMERIC FORM, RING STRUCTURE, AND LINKAGE IN THE C-13-NMR SPECTRA OF OLIGOMERS AND POLYMERS CONTAINING D-FRUCTOSE - MALTULOSE, ISOMALTULOSE, SUCROSE, LEUCROSE, 1-KESTOSE, NYSTOSE, INULIN, AND GRASS LEVAN

13C-N.m.r. spectroscopy has been used to determine the equilibrium composition of solutions of maltulose and isomaltulose in deuterium oxide. Resonance assignments have been made for maltulose, isomaltulose, sucrose, leucrose, 1-kestose, nystose, inulin, and grass levan. Some earlier assignments for sucrose and grass levan are corrected. The resonances of the D-glucopyranosyl group in maltulose and isomaltulose have been observed to be sensitive to the ring and anomeric forms of the adjacent D-fructose residue. Spin-lattice relaxation-times (T1) and nuclear Overhauser enhancement factors (n.O.e.f.) for the carbon atoms of the D-fructofuranosyl residues of inulin have been measured, and used in conjunction with deuteration, to aid in resonance and linkage assignments. © 1979.