Arabinoxylans oligosaccharides from enzymic hydrolyzates

Several xylo-oligosaccharides of d.p. 2-7 have been isolated from enzymic hydrolyzates of terrestrial-plant D-xylans, arabinoxylans, arabino-4-O-methylglucuronoxylans, and 4-O-methylglucuronoxylans by the action of endo-xylanases,5,6,38-40,42-44,47,181,215-217,222,228 236,247-250, 254,256,258-261 an(j have been shown to constitute a series of /3-D-(l — 4)-linked D-xylo-oligosaccharides. 

The / -xylosidase of T. reesei was a rather large, probably dimeric enzyme and, like most other / -xylosidases, had an acidic pi-value (Table I). A / -xylosidase purified earlier from T. viride with a molecular weight of 101 kDa also had an isoelectric point pi 4.45 (5). In addition to p-nitrophenyl-/ -xylopyranoside and xylo-oligosaccharides, the / -xylosidase of T. reesei also showed activity with p-nitrophenyl-a-arabinofuranoside as substrate, but did not hydrolyze arabinan or release arabinose from arabinoxylan. The purified a-arabinosidase, however, was capable of effecting both the latter hydrolyses (26, Table II). The isoelectric point of the a-arabinosidase of T. reesei was pi 7.5 and its molecular weight 53 kDa (Table I). 

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