Fungal Cellulases of Glycosyl Hydrolase Family 7 Catalyze Lactose Condensation

β-1,4-Endoglucanase of glycosyl hydrolase family (GHF) 7 from a fungus Aspergillus oryzae catalyzed the condensation between lactose (Lac) and alkanols. With Lac as a glycosyl donor, methanol, ethanol, 1-butanol and 1-hexanol and 1,6-hexanediol (HD) could be aglycons. The maximal condensation was observed between 250 mM Lac and 1.5 M HD at 30°C, pH 5.0. Transglycosylation to HD occurred to a similar extent with Lac-β-pNP or with cellobiose-β-pNP as the sugar donors, while the condensation between N-acetyllactosamine and HD was negative. Lac-condensation activity was also observed with the cellulase from Fusarium oxysporum, which belongs to GHF7. These suggested that fungal cellulases belonging to GHF7 should possess an ability to perform the condensation using Lac as a glycosyl donor.