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

Abstract

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 K m 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 ( K m = 4.2 mM) and a series of natural β- d-glucosides ( K m for coniferin = 1.49 mM). 6. 6. Methyl-β- d-glucoside, gentiobiose, cellobiose and lactose are faintly or not at all hydrolyzed.