An efficient chemical-enzymatic synthesis of 4-nitrophenyl β-xylobioside: a chromogenic substrate for xylanases

4-Nitrophenyl-β-xylobioside was synthesized by an improved short chemical-enzymatic method, based on the use of xylobiose as a starting material. Xylobiose was prepared following extensive enzymatic digestion of birchwood xylan with xylanase T-6. The resulting digest, containing mainly xylobiose and xylose, was directly subjected to an acetylation step, which after silica gel chromatography, provided highly pure hexaacetate of xylobiose. Bromination with HBr in acetic acid gave in quantitative yields the corresponding bromide, which after the coupling and deprotection steps, afforded the target 4-nitrophenyl-β-xylobioside.