Purification and characterization of two extracellular β-glucosidases fromAspergillus nidulans

Two β-glucosidases, P-I and P-II, were purified from the culture filtrate of Aspergillus nidulans. The Mr values of P-I and P-II were about 125 000 and 50 000, respectively. The isoelectric point, optimal pH and temperature, Michaelis constants for several substrates and inhibition constants for glucose and glucono-δ-lactone of each enzyme were determined. We conclude that the high affinity toward cellobiose and low inhibition by glucose of these enzymes may offer significant advantages in improving cellulose hydrolysis.