Studies on glycosidases and glucanases in Thaumetopoea pityocampa larvae—II. Purification and some properties of a broad specificity β-d-glucosidase

1. 1. A β- d -glucosidase was purified from Thaumetopoea pityocampa larvae (Lepidoptera Thaumetopoeidae). 2. 2. It was found to be homogenous on electrofocusing and on electrophoresis. 3. 3. The enzyme has a pI of 3.60 and an optimum pH of 6.0. 4. 4. The Km for p- nitrophenyl-β- d -glucoside is 0.39 mM. The enzyme has a broad specificity; it also hydrolyzes the p-nitrophenyl derivatives of β- d -galactose, β- d -fucose, and to a lower extent, of β- d -xylose. From the kinetic parameters we concluded that this enzyme is a β- d -glucosidase/β- d -fucosidase with a secondary β- d -galactosidase activity. 5. 5. The enzyme hydrolyzes sophorose and laminaribiose (Km = 4.2 mM) and a series of natural β- d -glucosides (Kmforconiferin = 1.49 mM). 6. 6. Methyl-β- d -glucoside, gentiobiose, cellobiose and lactose are faintly or not at all hydrolyzed.