β-Glucosidase of Penicillium funiculosum. I. Purification

Abstract

A strain of Penicillium funiculosum, isolated in this laboratory, produced in high yield both endo- and exo-glucanases and β-glucosidases, which were suitable for the saccharification of cellulosic materials. The isolation of the β-glucosidase of this organism, which differs from other β-glucosidases of fungi in its substrate specificity, by preparative electrophoresis, is described in this article. The organism was grown on a lactose-casein medium and the culture filtrate concentrated by ammonium sulfate precipitation and dialysis. Electrophoresis was carried out on large slabs of polyacrylamide gel in an anodicrun in the presence of borate at pH 7. After elution of active fractions, a cathodic run was made at pH 6.0. Two precipitations with ammonium sulfate resulted in a homogeneous enzyme (specific activity 174 IU/mg). A second isozyme was also produced by P. funiculosum on cellulose-wheat bran medium. This isozyme was purified by electrophoresis at pH 7.0 in the absence of borate and was obtained free from other isozymes of β-glucosidase and cellulases.