Substrate specificities of Aspergillus terreus α-arabinofuranosidases

The substrate specificities of three purified Aspergillus terreus alpha-arabinofuranosidases, pi 7.5, 8.3 and 8.5, were studied using various isolated arabinose-containing polysaccharides and oligosaccharides as substrates. In addition, their mode of action was compared with those of some other arabinose-releasing enzymes. All three A. terreus alpha-arabinofuranosidases preferred branched pectic polysaccharides, such as sugar beet arabinan and beta-1,4-arabinogalactans as substrates, but they were also able to release arabinose from linear arabinan, beta-1,3/1,6-arabinogalactans and different arabinoxylans. alpha-Arabinofuranosidases pi 7.5 and pi 8.5 were able to hydrolyse arabinose from oligosaccharide mixtures of wheat flour and larchwood arabinoxylans, forming arabinose and linear xylo-oligosaccharides. However, isolated arabinoxylo-oligosaccharides (DP 3-5) with arabinose substituted at O-3 of an internal xylose residue were only poorly degraded. Arabinose linked to O-2 of either internal or non-reducing end xylose residues was not hydrolysed. (C) 1998 Elsevier Science Ltd. All rights reserved.