Purification and properties of the cell-associated beta-xylosidase from Aureobasidium

beta-Xylosidase was extracted from Aureobasidium sp. ATCC 20524 and purified to homogeneity. The molecular mass was estimated at 411 kDa. The enzyme contained 15.3% (w/w) carbohydrate. The optimum pH and temperature were pH 3.5 and 80 degrees C, respectively. The enzyme was stable at pH 3.5-9 after 3 h and at 80 degrees C after 15 min. The Michaelis constant (K(m)) and maximum velocity (V(max)) toward p-nitrophenyl-beta-D-xyloside were 2.0 mmol l(-1) and 0.94 mmol min(-1) mg(-1) protein, respectively. The enzyme was inhibited strongly by mercury, lead, and copper ions.