A glucose-tolerant beta-glucosidase was purified to homogeneity from prune (Prunus domestica) seeds by successive ammonium sulfate precipitation, hydrophobic interaction chromatography and anion-exchange chromatography. The molecular mass of the enzyme was estimated to be 61 kDa by SDS-PAGE and 54 kDa by gel permeation chromatography. The enzyme has a pl of 5.0 by isoelectric focusing and an optimum activity at pH 5.5 and 55 degrees C. It is stable at temperatures up to 45 degrees C and in a broad pH range. Its activity was completely inhibited by 5 mM of Ag+ and Hg2+. The enzyme hydrolyzed both p-nitrophenyl beta-D-glucopyranoside with a K-m of 3.09 mM and a V-max of 122.1 mu mol/min mg and p-nitrophenyl beta-D-fucopyranoside with a K-m of 1.65 mM and a V-max of 217.6 mu mol/min mg, while cellobiose was not a substrate. Glucono-delta-lactone and glucose competitively inhibited the enzyme with K-i values of 0.033 and 468 mM, respectively. (C) 2011 Elsevier Ltd. All rights reserved.