Alkaline Phosphatase and Other Hydrolyases Produced by Cenococcum graniforme , an Ectomycorrhizal Fungus

Abstract

Cell extracts of Cenococcum graniforme have been found to contain the following hydrolytic enzymes: protease, esterase, α- d -galactopyranosidase, β- d -galactopyranosidase, α- d -mannopyranosidase, β- d -xylopyranosidase, α- d -glucopyranosidase, β- d -glucopyranosidase, and alkaline phosphatase. Sulfatase, inorganic pyrophosphatase, and β- d -mannopyranosidase were not detected in the extracts. β- d -Xylopyranosidase and α- d -mannopyranosidase were most active in the neutral pH range, protease and phosphatase were most active in the alkaline pH range, and other enzymes were most active in the acidic pH range. These enzymes showed a high association with cell wall material, and the release of enzymes from the cells into the culture fluid appeared to occur only when the cells were undergoing autolysis. Alkaline phosphatase in C. graniforme is a constitutive enzyme, and examination of the alkaline phosphatase following a purification of 265-fold produced the following characteristics: pH optimum of 9.5, M r of 60,000, K m of 2.1 × 10 -4 M for p -nitrophenylphosphate, and activation energy for hydrolysis of the substrate at 9.9 kcal (1 cal = 4.184 J)/mol.