Preparation of arabinoxylobiose from rye xylan using family 10 Aspergillus aculeatus endo-1,4-β-d-xylanase

Commercial xylanase preparation Shearzyme®, which contains the glycoside hydrolase family 10 endo-1,4-β-d-xylanase from Aspergillus aculeatus, was used to prepare short-chain arabinoxylo-oligosaccharides (AXOS) from rye arabinoxylan (AX). A major AXOS was formed as a hydrolysis product. Longer AXOS were also produced as minor products. The pure GH10 xylanase from A. aculeatus was used as a comparison to ensure that the formed AXOS were consequence of the endoxylanase‘s function instead of some side enzymes present in Shearzyme. The major AXOS was purified and the structure confirmed with various analysis methods (TLC, HPAEC-PAD, MALDI-TOF-MS, and one- and two-dimensional NMR spectroscopy with nano-probe) as α-l-Araf-(1 → 3)-β-d-Xylp-(1 → 4)-d-Xylp (arabinoxylobiose). This is the first report on 13C NMR data of pure arabinoxylobiose. The yield of arabinoxylobiose was 12% from the quantified hydrolysis products. In conclusion, GH10 endoxylanase from A. aculeatus is thus able to cut efficiently the xylosidic linkage next to the arabinofuranosyl-substituted xylose unit which is not typical for all the GH10 endoxylanases. Interestingly, pure A. aculeatus xylanase showed notably activity towards p-nitrophenyl-β-d-xylopyranose. In previously studies longer AXOS have been produced with Shearzyme but the formation of short-chain AXOS by A. aculeatus GH10 xylanase has not been studied before.