Methyl β-d-xylotrioside was used as a non-reducing substrate to investigate the stereochemistry of hydrolysis of, β-1,4-xylopyranosidic linkage by purified endo-β-1,4-xylanases (EC 18.104.22.168) of Trichoderma reesei, employing 1H NMR spectroscopy. The fungus produces one acidic species (pI 4.8-5.5), designated as EXI, and one alkaline species (pI 8.5-9.0), designated as EXII. Both enzymes were found to cleave the xylotrioside predominantly to methyl β-d-xyloside and xylobiose. Monitoring of the intensity of the H-1 signals of α- and β-xylobiose during the time course of hydrolysis clearly showed that both enzymes liberate the β-anomer of xylobiose, i.e. a product with anomeric configuration identical with that of the cleaved glycosidic linkage. This means that both EXI and EXII belong to the so-called retaining glycanases that utilize the double displacement reaction mechanism of hydrolysis. © 1994.
Biely, P., Kremnický, L., Alföldi, J., & Tenkanen, M. (1994). Stereochemistry of the hydrolysis of glycosidic linkage by endo-β-1,4-xylanases of Trichoderma reesei. FEBS Letters, 356(1), 137–140. https://doi.org/10.1016/0014-5793(94)01248-2