The purification and characterization of a beta-glucosidase from Alcaligenes faecalis

The beta-glucosidase from Alcaligenes faecalis has been purified to homogeneity (880-fold purification, 11% yield) using a combination of classical techniques and medium pressure ion-exchange chromatography. It is a dimeric enzyme of monomer molecular weight 50,000 and has no specific requirement for divalent metal ions. It has a high specificity for beta-glucosides and hydrolyses a wide variety of different chemical types wit retention of configuration at the anomeric centre. It has no exo-beta-1,4-glucanase activity. It is reversibly inhibited by a variety of sugars which have been shown previously to be very active against glucosidases, suggesting a normal mechanism of action. Measured Km values for cellobiose and p-nitrophenyl beta-D-glucopyranoside are quite low (0.70 and 0.08 mM, respectively), making this a good choice for cocloning into a cellulase system optimized for glucose production.