β-Glucosidase from Lepista flaccida an Edible Mushroom

摘要

A β-glucosidase was purified 5.0-fold with ammonium sulfate precipitation from the fruiting body of lepista flaccida, an edible mushroom. The enzyme exhibited maximum activity at pH 3.0 and 60 °C when p-nitrophenyl-β-D-glucoside was used as a substrate. K_m and V_(max) values were calculated as 1.06 mM and 5.8 U/mg protein, respectively. The enzyme was quite stable over a broad range of pH (2.0-9.0) at 4 °C after 24 h incubation. The enzyme activity was conserved about 45 % after 12 h incubation at 60 °C. Metal ions such as Na~+, Li~+, Mn~(2+), Zn~(2+), Hg~(2+) Co~(2+) and Cu~(2+) and chemicals such as EDTA, phenylmethyl sulfonyl fluoride, β-mercaptoethanol and dithiothreitol had a little negative or positive effect on the enzyme activity. The resistance of the partially purified enzyme to some metal ions and chemicals, along with the pH and thermal stability, can make it very attractive for future applications in industry.