Dephosphorylation of phytate by using the Aspergillus niger phytase with ahigh a affinity for phytate

A phytase (EC 3.1.3.8) with a high affinity for phytic acid was found in As pergillus niger SK-57 and purified to homogeneity in four steps by using io n-exchange chromatography (two types), gel filtration, and chromatofocusing . Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified enzyme gave a single stained band at a molecular mass of approximately 60 kDa. The Michaelis constant of the enzyme for phytic acid (18.7 +/- 4.6 mu M) was statistically analyzed. In regard to the orthophosphate released fro m phytic acid, a significant difference between a low K-m phytase from A. n iger SK-57 and a high K-m phytase from Aspergillus ficuum was recognized.