Some properties of partially purified phytase from Aspergillus niger

Phytase was purified from Aspergillus niger culture fluid by molecular sieve filtration on Sephadex G-200, followed by thermal inactivation of acid phosphatase and CM-cellulose chromatography. The 12-fold purified enzyme had two pH optima at 2.7 and 5.5 and was characterized by high thermal stability in alkaline environment and broad substrate specificity. The Michaelis constant of phytase relative to myo-inositol hexaphosphate sodium salt is 4.8 X 10(-4) M and activation energy 9,217 cal/mole. The molecular weight of the enzyme is estimated at 200,000.