Isolation of a phytase with distinctive characteristics from an edible mushroom, Pleurotus eryngii.

From the fresh fruiting bodies of the mushroom Pleurotus eryngii a phytase with a molecular mass of 14 kDa was isolated. The isolation protocol entailed ion exchange chromatography on DEAE-cellulose and CM-cellulose, affinity chromatography on Affi-gel blue gel, and ion exchange chromatography on Q-Sepharose. The phytase was unadsorbed on DEAE-cellulose, CM-cellulose and Affi-gel blue gel, and adsorbed on Q-Sepharose. It appeared as a single band in SDSPAGE. It exhibited maximal activity at around 37°C. Its activity underwent little changes over the range of pH 3.0 to 9.0. The aforementioned characteristics are different from those of animal, plant and bacterial phytases. The low molecular mass and pH stability of P. eryngii phytase also distinguish it from mushroom phytases and other fungal phytases reported earlier. The purified enzyme exhibited a broad substrate specificity on a range of phosphorylated compounds, and the phytase demonstrated the N-terminal sequence ADNVYRHDNN which shows little homology to known phytases. It inhibited proliferation of human nasopharyngeal carcinoma CNE2 cells, hepatoma HepG2 cells and breast cancer MCF7 cells with an IC(50) of 1.9 μM, 2.9 μM, and 1.0 μM, respectively.