转基因玉米中植酸酶蛋白沉淀条件探索

Studies on Precipitation Conditions of Phytase Protein from Transgenic Corn

为了对玉米中表达的植酸酶蛋白的酶学性质进行深入研究,以转基因玉米籽粒中提取的植酸酶粗提液为研究材料,探索了植酸酶和总蛋白的溶解度与硫酸铵饱和度之间的关系,结果显示在0～60%硫酸铵饱和度范围沉淀的植酸酶仅占初提液中总植酸酶含量的1.85%,而在此范围内沉淀的总蛋白却占初提液的总蛋白含量的57%,植酸酶比活为0.44 U/mg;在60%～80%硫酸铵饱和度范围沉淀的植酸酶和总蛋白分别占初提液中各自含量的58%和10%,植酸酶比活为84.4 U/mg;在80%～90%硫酸铵饱和度范围沉淀的植酸酶收率占初提液中含量的1.9%。因此选用60%～80%硫酸铵饱和度分级沉淀植酸酶,在此条件得到的植酸酶比活比粗提液的植酸酶比活（13.8 U/mg）高6.1倍。

In order to carry out further studies on enzymology properties of phytase protein expressed in transgenic corn seeds, we studied the relations between solubility of phytase and total protein and the saturation of ammonium sulfate with crude phytase extracted from transgenic corn seeds as material. The results showed that in the saturation range 0-60% of ammonium sulfate, the precipitated phytase only accounted for 1.85% of the total phytase in initial extraction, while the precipitated protein in the same saturation range accounted for 57% of the total protein in initial extraction. The specific activity of phytase was 0.44 U/mg. In the saturation ranging from 60% - 80% of ammonium sulfate, the precipitated phytase and total protein accounted for 58% and 10% of the total in initial extraction, respectively. And the specific activity of phytase was 84.4 U/mg. In the saturation ranging from 80% - 100% of ammonium sulfate, the yield of precipitated phytase accounted for 1.9% of the initial extraction. Therefore, the saturation ranging from 60% - 80% of ammonium sulfate was set as the optimal condition to precipitate phytase. The specific activity of phytase obtained under this condition was 6.1 times higher than the crude extraction （13.8 U/mg）.