Characterisation by 1H NMR spectroscopy of oligosaccharides derived from alkali-extractable wheat-flour arabinoxylan by digestion with endo-(1->4)-β-D-xylanase III from Aspergillus awamori

Abstract

Alkali-extractable wheat-flour arabinoxylan, treated with endo-(1 -> 4)-beta-D-xylanase III from Aspergillus awamori CMI 142717, was fractionated by Bio-Gel P-2 size exclusion chromatography at 60‹C. Column fractions, corresponding to oligosaccharides with degrees of polymerisation from 5 to 10, were collected, and subfractionated by high performance anion-exchange chromatography on CarboPac PA-1. The structures of the oligosaccharides thus obtained were elucidated by 1H NMR spectroscopy, showing chains of (1 -> 4)-linked beta-D-xylopyranosyl residues differently substituted at O-3 and / or O-2,3 with alpha-L-arabinofuranosyl groups. The structures were different from those obtained with endo-(1 -> 4)-beta-D-xylanase I of the same xylanolytic enzyme system.