Purification and Characterization of a β-Glucosidase with β-Xylosidase Activity from Aspergillus sojae

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A β-glucosidase(EC3.2.1.21)was purified as an electrophoretically homogeneous protein from a solid culture of Aspergillus sojae. The molecular mass of the purified enzyme was estimated to be 250kDa by gel filtration chromatography and 118 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE). The isoelectric point of the enzyme was 3.80. The maximum velocity of ρ-nitrophenyl β-D-glucopyranoside degradation by the β-glucosidase was attained at 60°C and at pH 5.0. The purified enzyme was stable from pH 6.0 to 8.0, and up to 50°C. The activity of the enzyme was significantly inhibited by Hg^<2+> and Cu^<2+> and stimulated by Mn^<2+> and Fe^<3+>. The purified enzyme hydrolyzed β-D-xylopyranosides as well as β-D-glucopyranosides ; the K_m and V_<max> values on ρ-nitrophenyl β-D-glucopyranoside were 0.14mM and 16.7μmol/min/mg protein, and on ρ-nitrophenyl β-D-xylopyranoside 0.51mM and 12.2μmol/min/mg protein, respectively.
社団法人日本生物工学会の論文
1999-04-25