Purification and properties of an endo-α-mannan hydrolase from the mushroom Volvariella volvacea

Abstract

The enzyme, endo-α-mannanase, from culture filtrate of a mushroom Volvariella volvacea has been purified 73-fold by acetone precipitation, ion-exchange chromatography (DEAE-Sephadex), and gel-permeation chromatographies on Bio-Gel P-300 and on Sephacryl S-200 columns. The enzyme preparation gave a single protein band on sodium dodecyl sulfate-disc gel electrophoresis at pH 6.8 and has a molecular weight of approx. 56,000. It has no α- or β-mannosidase activity and does not act on β-gluco-or galactomannan. The enzyme shows maximum activity on baker's yeast α-mannan at pH 5.0 and at 55 °C, and is fairly stable between pH 3 and 6 and temperatures up to 50 °C. The K m is 32.25 mg mannan/ml. Enzyme activity is inhibited by Hg 2+, sodium azide, iodoacetic acid, EDTA, and Ag +, in decreasing order.