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Carbohydrate research

Proton and carbon NMR chemical-shift assignments for [beta-D-Fru f-(2-->1)]3-(2<==>1)-alpha-D-Glc p (nystose) and [beta-D-Fru f-(2-->1)]4-(2<==>1)-alpha-D-Glc p (1,1,1-kestopentaose) from two-dimensional NMR spectral measurements.


PMID 8358742

Abstract

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 13C chemical-shift assignments were made. The 1H 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 1JCH coupling patterns between C-1 and H-1. Assignments of 13C and 1H 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-glucopyr anoside (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 13C chemical shifts, it appears that the chemical environment of inulin is not attained in nystose, and only partially attained in 1,1,1-kestopentaose.