Purification and characterization of two extracellular beta-glucosidases from Aspergillus nidulans

Two beta-glucosidases, P-I and P-II, were purified from the culture filtrate of Aspergillus nidulans. The M(r) 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-delta-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.