EFFECT OF SIDE-GROUPS ON THE ACTION OF BETA-XYLOSIDASE FROM TRICHODERMA-REESEI AGAINST SUBSTITUTED XYLO-OLIGOSACCHARIDES

The action of beta-xylosidase from Trichoderma reesei against differen t substituted xylo-oligosaccharides was studied, The enzyme cleaved of f all unsubstituted xylose units from the non-reducing end of 1,2-link ed uronic acid substituted xylooligosaccharides, Surprisingly, an L-ar abinofuranosyl group linked alpha-1,3 to the xylopyranosyl ring was fo und to protect the beta-1,4-xylosidic linkage before the substituted x ylose unit from being cleaved by the beta-xylosidase, Most probably th e 1,3-linked substituent sterically hinders the hydrolysis. According to the results of the present work, beta-xylosidase of T, reesei is no t able to remove all unsubstituted xylose units from the non-reducing end of substituted xylo-oligosaccharides, as had been believed previou sly.