Purification and Some Properties of β-Glucosidase from Streptomyces sp

β-Glucosidases I, II, and III were isolated from the culture filtrate of a Streptomyces sp. by ammonium sulfate fractionation, hydroxylapatite column chromatography, filtration on Bio-Gel P-100, and DE-52 column chromatography. β-Glucosidase III had a single active band on disc-gel electrophoresis. Its optimum pH and temperature for activity were 6.0 and 60°C, respectively. The isoelectric point and molecular weight of the enzyme were pH 4.5 and 45,000, respectively. From an experiment using 14C-labeled glucose, gentiobiose seemed to be formed from laminaribiose as isomaltose is formed from maltose by fungal α-glucosidase. The enzyme showed transglucosylation and produced gentiobiose from β-gluco-disaccharides and 4-O-β-d-glucopyranosyl-d-manno-pyranose (epicellobiose). The enzyme acted on phenolic β-d-glucosides to produce unknown transfer products.