CONFORMATIONAL-ANALYSIS D-FRUCTANS .7. PROTON AND CARBON NMR CHEMICAL-SHIFT ASSIGNMENTS FOR [BETA-D-FRUF-(2-]1)]3-(2[--]1)-ALPHA-D-GLCP (NYSTOSE) AND [BETA-D-FRUF-(2-]1)]4-(2[--]1)-ALPHA-D-GLCP (1,1,1-KESTOPENTAOSE FROM 2-DIMENSIONAL NMR SPECTRAL MEASUREMENTS

The proton chemical-shift assignment of nystose (1) [beta-D-fructofuranosyl-(2 --> 1)-beta-D-fructofuranosyl-(2 --> 1)-beta-D-fructofuranosyl-(2 <----> 1)-alpha-D-glucopyranoside], was determined by using two-dimensional (2D) NMR spectral methods, and corrections of, and additions to the previous C-13 chemical-shift assignments were made. The H-1 peak of H-1 of the D-glucosyl group was determined by its chemical shift. Signals from fructose-1 were distinguished by the observation of long-range C-H coupling between H-1 of the D-glucosyl group and C-2 of fructose-1. The distinction between fructose-2 and fructose-3 was made by the different 1J(CH) coupling patterns between C-1 and H-1. Assignments of C-13 and H-1 chemical shifts of the related dp 5 compound, beta-D-fructofuranosyl-(2 --> 1)-beta-D-fructofuranosyl-(2 --> 1)-beta-D-fructofuranosyl-(2 --> 1)-beta-D-fructofuranosyl-(2 <----> 1)-alpha-D-glucopyranoside (1,1,1-kestopentaose, 2) are also reported here with comparisons of its spectral data with the data from 1-kestose, nystose and inulin. Based on differences in C-13 chemical shifts, it appears that the chemical environment of inulin is not attained in nystose, and only partially attained in 1,1,1-kestopentaose.