Purification and characterization of an aspecific glycoside hydrolase from the anaerobic ruminal fungus Neocallimastix frontalis

Abstract

A glycoside hydrolase characterized by β-fucosidase (EC 3.2.1.38) and β-glucosidase (EC 3.2.1.21) activities was purified from the culture medium of the anaerobic ruminal phycomycete Neocallimastix frontalis grown on 0.5% Avicel. The enzyme had a molecular mass of 120 kilodaltons and a pI of 3.85. Optimal activity against p-nitrophenyl-β-D-fucoside and p-nitrophenylβ-D-glucoside occurred at pH 6.0 and 50°C. The β-fucosidase and β-glucosidase activities were stable from pH 6.0 to pH 7.8 and up to 40°C. They were both inhibited by gluconolactone, sodium dodecyl sulfate, p-chloromercuribenzoate, and Hg2+ cation. The enzyme had K(m)s of 0.26 mg/ml for p-nitrophenyl-β-D-fucoside and 0.08 mg/ml for p-nitrophenyl-β-D-glucoside. The purified protein also had low β-galactosidase activity.