MODE OF ACTION OF (1-]4)-BETA-D-ARABINOXYLAN ARABINOFURANOHYDROLASE (AXH) AND ALPHA-L-ARABINOFURANOSIDASES ON ALKALI-EXTRACTABLE WHEAT-FLOUR ARABINOXYLAN

Arabinoxylan-derived oligosaccharides were treated with (1 --> 4)-beta -D-arabinoxylan arabinofuranohydrolase (AXH) and two types Of alpha-L- arabinofuranosidase, A and B. Analysis of reaction products by high pe rformance anion-exchange chromatography indicated the removal of arabi nofuranosyl groups from singly substituted xylopyranosyl residues. In addition, differences in the specificity of these enzymes towards the various differently substituted oligosaccharides were observed. H-1 NM R spectroscopy and methylation analysis of alkali-extractable wheat-fl our arabinoxylan treated with AXH confirmed the specificity of AXH tow ards (1 --> 3)-linked arabinofuranosyl groups on singly substituted xy lopyranosyl residues. With these techniques, alpha-L-arabinofuranosida se B was found to cause minor changes in (1 --> 2)- and (1 --> 3)-link ed arabinofuranosyl groups on doubly substituted xylopyranosyl residue s.