Environmental Science and Engineering Department, Huazhong Agricultural University, Wuhan 430070, China.
Plant Physiol Biochem. 2011 Feb;49(2):146-50. doi: 10.1016/j.plaphy.2010.11.004. Epub 2010 Nov 12.
Phytase is involved in many physiological activities in plants including phosphorus metabolism and stress response. The effects of arsenic on phytase activities in arsenic-hyperaccumulator Pteris vittata were determined. Two arsenic-sensitive ferns (Pteris ensiformis and Nephrolepis exaltata) were included for comparison purpose. Fern phytase was extracted with Tris-HCl buffer (pH 7.6) followed by ammonium sulfate partial purification to characterize its properties and arsenic stress responses. The phytase showed an optimum pH of 5.0 and temperature of 40 °C except for P. vittata with 40-70 °C. Phytase from P. vittata was the first plant-phytase showing high heat resistance with no loss of activity by heating it at 70 °C, which may have application in feed industry. Phytase activity was inhibited by arsenate but not by arsenite. The fact that P. vittata phytase was the most heat-tolerant (40-70 °C) and had the highest resistance to arsenate among the three ferns suggest that phytase may play a role in arsenic detoxification and arsenic hyperaccumulation in P. vittata.
植酸酶参与植物的许多生理活动，包括磷代谢和应激反应。本研究测定了砷对砷超富集植物蜈蚣草中植酸酶活性的影响。同时选取了两种对砷敏感的蕨类植物（井栏边草和肾蕨）进行比较。采用 Tris-HCl 缓冲液（pH7.6）提取蕨类植物植酸酶，然后用硫酸铵进行部分纯化，以研究其性质和砷胁迫响应。结果表明，除了蜈蚣草的最适温度为 40-70°C 外，该酶的最适 pH 值为 5.0，最适温度为 40°C。蜈蚣草的植酸酶是第一种具有高热稳定性的植物植酸酶，在 70°C 下加热后没有失去活性，这在饲料工业中可能有应用价值。砷酸盐抑制植酸酶活性，但亚砷酸盐不抑制。三种蕨类植物中，蜈蚣草的植酸酶耐热性最强（40-70°C），对砷酸盐的抗性最高，这表明植酸酶可能在蜈蚣草的砷解毒和砷超积累中发挥作用。
