State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
Bioresour Technol. 2010 Jun;101(11):4125-31. doi: 10.1016/j.biortech.2010.01.001. Epub 2010 Feb 9.
A novel phytase was isolated from Aspergillus ficuum NTG-23 with a procedure involving ion-exchange chromatography on DEAE-cellulose, CM-cellulose and FPLC-gel filtration on Superdex 75. The protein exhibited a molecular mass of 65.5kDa in gel filtration and SDS-PAGE. It possessed an optimal pH of 1.3 and an optimal temperature of 67 degrees C, and manifested a K(m) of 0.295mM and a V(max) of 55.9nmol (phosphate)/min. Phytase activity was not significantly affected by metal ions such as Ca(2+), Mg(2+), Mn(2+), Zn(2+), but was slightly stimulated in the presence of EDTA. The phytase was stable at 60 degrees C with no obvious loss of activity upon its incubation at 70 degrees C for 20min. The enzyme exhibited a broad substrate selectivity and showed strong resistance toward pepsin and trypsin. The unique properties suggest that the phytase has the potential to be useful as an animal feed supplement.
从曲霉 NTG-23 中分离到一种新型植酸酶，该过程包括 DEAE-纤维素、CM-纤维素离子交换层析和 Superdex 75 FPLC 凝胶过滤。该蛋白在凝胶过滤和 SDS-PAGE 中的分子量为 65.5kDa。它的最适 pH 值为 1.3，最适温度为 67°C，Km 值为 0.295mM，Vmax 值为 55.9nmol（磷酸盐）/min。植酸酶活性不受 Ca(2+)、Mg(2+)、Mn(2+)、Zn(2+)等金属离子的显著影响，但在 EDTA 存在下略有刺激。该植酸酶在 60°C 下稳定，在 70°C 孵育 20min 后没有明显的活性损失。该酶对胃蛋白酶和胰蛋白酶具有较强的抗性，具有广泛的底物选择性。这些独特的性质表明，该植酸酶有可能作为一种动物饲料添加剂有用。
