THE ARRANGEMENT OF BRANCHING IN AN ARABINO-XYLAN FROM WHEAT FLOUR

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Abstract
The manner in which L-arabinofuranose branches are arranged along the xylan chain of the pentosans has been examined. The approach used was based on the fact that D-xylose units engaged in branching are resistant to periodate oxidation whereas other sugar residues are readily attacked. Selective degradation of oxidized portions of the polymer with phenyl-hydrazine or sulphurous acid enabled the isolation of fragments which corresponded to branch points in the original pentosans. D-Xylose and xylobiose were the major products obtained, and xylotriose a minor product. The results indicate that L-arabinose branches of the polysaccharide occur sometimes on isolated D-xylose residues, sometimes on two adjacent D-xylose units, less frequently on three, but not on four, five, etc., consecutive D-xylose residues along the chain.