Fungal Glycosidases. V. Purification and Properties of an Extracellular exo-(1→3)-β-D-Glucosidase from Trichophyton mentagrophytes

Abstract

An exo-(1→3)-β-D-glucosidase was isolated from the culture filtrate of the fungus Trichophyton mentagrophytes by ammonium sulfate fractionation, gel chromatography on Sephadex G-200 equilibrated with 0.1M sodium phosphate buffer (pH 7.5), and ion exchange chromatography on DEAE-Sephadex A-50. The enzyme was purified 304 fold, with a recovery of 15%. The Km value of the enzyme with pnitrophenyl-β-D-glucopyranoside was 3.1 mM. The enzyme was strongly inhibited by Ag⁺, Hg²⁺, Cu²⁺ and Co²⁺ ions and also by N-bromosuccinimide and I₂. This enzyme hydrolyzed p-nitrophenyl-β-D-glucopyranoside but did not show any activity towards p-nitrophenyl-α-D-glucopyranoside or other p-nitrophenyl-glycosides. The enzymes also hydrolyzed (1→3)-β-linked glucosides, but not (1→4)-β-and (1→6)-β-linked glucosides. When the enzyme hydrolyzed (1→3)-β-linked oligo and polyglucosides, the only product identified by paper chromatography was glucose monomer. The molecular weight of the enzyme, as determined by sodium dodecyl sulfate disc gel electrophoresis, was 4.9×10⁴ daltons.