Purification and mode of action of two different arabinoxylan arabinofuranohydrolases from Bifidobacterium adolescentis DSM 20083

Two novel arabinofuranohydrolases (AXH-d3 and AXH-m23) were purified from B ifidobacterium adolescentis DSM 20083. Both enzymes were induced upon growt h of Bi. adolescentis on xylose and arabinoxylan-derived oligosaccharides. They were only active with arabinoxylans and therefore denoted as arabinoxy lan arabinofuranohydrolases. Their optimal activity was at pH 6 and 30-40 d egrees C. They were very specific in their mode of action and were clearly different from AXH-m from Aspergillus awamori. AXH-m23 released only arabin osyl groups, which were linked to the C-2 or C-3 position of singly substit uted xylose residues in arabinoxylan oligomers. AXH-d3 hydrolysed C-3-linke d arabinofuranosyl residues of doubly substituted xylopyranosyl residues of arabinoxylans and arabinoxylan-derived oligosaccharides. No activity was o bserved with C-2-linked arabinofuranosyl residues of these doubly substitut ed xylopyranosyl residues, or against C-2- and C-3-linked arabinofuranosyl residues of singly substituted xylopyranosyl residues. The combination of A XH-d3 and AXH-m showed low debranching activity with highly substituted glu curonoarabinoxylans. However, arabinoxylan from wheat flour was debranched almost completely.