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

The enzyme, endo-alpha-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 alpha- or beta-mannosidase activity and does not act on beta-gluco-or galactomannan. The enzyme shows maximum activity on baker's yeast alpha-mannan at pH 5.0 and at 55 degrees C, and is fairly stable between pH 3 and 6 and temperatures up to 50 degrees C. The Km is 32.25 mg mannan/ml. Enzyme activity is inhibited by Hg2+, sodium azide, iodoacetic acid, EDTA, and Ag+, in decreasing order.