Centre de Recherches sur les Macromolécules Végétales, CNRS-Grenoble, B.P. 68, F-38402 Saint Martin d'Hères France
Abstract:
A 25.182-MHz 13C-n.m.r. spectrum of gum arabic allows unambiguous characterisation of all the C-1 resonances. These assignments have been confirmed by correlation of the modification of the intensities of these signals after controlled acid hydrolysis and characterisation of the released fragments. The resonances of the other carbons have been assigned through partial relaxed T1 spectra of the polysaccharides obtained by graded degradation of the gum. These results indicate gum arabic to consist mainly of a (1→3)-β-
-galactan core with (1→6)-β-
-galacto-pyranosyl branches and with -
-arabinofuranosyl-(1→3)--
-arabinofuranosyl and -
-rhamnopyranosyl-(1→4)-β-
-glucopyranosyluronic acid groups attached to positions 3 and 6, respectively, of the branch units.