Evaluation of the transglycosylation activities of a GH 39 β-d-xylosidase for the synthesis of xylose-based glycosides

The ability of GH 39 β-d-xylosidase (XylBH39) from Bacillus halodurans to catalyze transxylosylation reactions, particularly for the production of alkyl xylosides, has been investigated using p-nitrophenyl (pNP) β-d-xylopyranoside, xylobiose and xylotriose. Furthermore wheat bran, being rich in xylo-oligosaccharides after enzymatic treatment with an endoxylanase, was used as a source of xylosyl donors. The autocondensation of pNP β-d-xylopyranoside was characterized by poor regioselectivity and the production of a variety of short (di- and trimers) oligosaccharides. Compared to xylobiose, xylotriose was a better donor molecule for XylBH39-mediated transxylosylation of primary alcohols presenting chain length from 1- to 5-carbon atoms. Using a wheat bran hydrolysate, generated using an endoxylanase, it was possible to perform XylBH39-mediated transxylosylation of propan-1-ol to produce propyl β-d-xylopyranoside. This enzymatic process led to synthesis of 0.9 g of propyl β-d-xylopyranoside from 20 g of destarched wheat bran.