Action of a GH 51 α-l-arabinofuranosidase on wheat-derived arabinoxylans and arabino-xylooligosaccharides

The substrate specificity of an arabinofuranosidase (AbfD3) from family 51 of glycoside hydrolase classification was investigated in order to precisely evaluate its catalytic abilities. AbfD3 activity on destarched wheat bran was poor and less than 1% of total arabinose was released. AbfD3 was also tested on arabinoxylans derived from destarched wheat bran that present different degrees of polymerization, A/X ratios, ferulic acid content and solubility. Results indicated that AbfD3 can hydrolyze polymeric arabinoxylans, even if this action was moderate when compared to the efficient hydrolysis of oligosaccharides. The limited action of AbfD3 on polymeric arabinoxylans is discussed with regard to the heterogeneous distribution of the arabinose residues along the xylan main chain, the insolubility of arabinoxylans and to the presence of disubstituted xylose or feruloylated arabinose.