1H-N m.r. study of enzymatically generated wheat-endosperm arabinoxylan oligosaccharides: structures of hepta- to tetradeca-saccharides containing two or three branched xylose resides
1992
The structures of hepta- to tetradeca-saccharides, generated by digestion of wheat-endosperm arabinoxylan with endo-(1 leads to 4)-beta-D-xylanase, and isolated by gel-permeation chromatography on Bio-Gel P-6 and high-performance anion-exchange chromatography with pulsed amperometric detection (h.p.a.e.-p.a.d.), were elucidated using monosaccharide and methylation analysis, f.a.b.-m.s., and 1H-n.m.r. spectroscopy. The structures identified had two branching elements, leads to 4)[alpha-L-Araf-(1 leads to 3)]-beta-D-Xylp-(1 leads to and /or leads to 4)[alpha-L-Araf-(1 leads to 2)][alpha-L-Araf-(1 leads to 3)]-beta-D-Xylp-(1 leads to, directly connected to each other in all four possible combinations. The h.p.a.e.-p.a.d. elution pattern showed that these combinations are not present in equal amounts. Also, compounds containing two 2,3-branched beta-D-Xylp residues separated by one or two unbranched beta-D-Xylp residues were found, and the presence of a tetradecasaccharide containing three 2,3-branched beta-D-Xylp residues was established.
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