The coding region of mpd gene corresponding to mature methyl parathion hydrolase (MPH) was heterologously overexpressed in Escherichia coli BL21 (DE3) by using pET expression system. The lactose-induced expression yield of MPH is increased 2-fold compared with IPTG as inducer. Furthermore, it was found that specific activity of MPH increased 48% by reducing the induction temperature to 22 degrees C. The addition of 25 mM lactose at 22 degrees C, the MPH activity of fermentation broth had a specific activity of 1.4 x 10(4) U/mg protein. Plasmid was no significant decrease in the modified medium. The optimal pH and temperature of MPH were 8.0 and 30 degrees C, respectively. Over a period of 5 months, the dried cells showed no significant decrease in the activity of the detoxifying enzymes. The crude enzymes in 50 mM citrate-phosphate buffer (pH 8.0) were able to degrade about 98% of the organophosphate pesticides sprayed on cabbage. The detoxification efficiency was superior to that of the treatments of water, detergent, and a commercially available enzyme product. Additionally, the products of pesticide hydrolysis generated by treatment with the enzyme extract were determined to be virtually nontoxic.

中文翻译：

---

甲基对硫磷水解酶的过表达及其在有机磷酸酯解毒中的应用。

通过使用pET表达系统，对应于成熟甲基对硫磷水解酶（MPH）的mpd基因的编码区在大肠杆菌BL21（DE3）中异源过表达。与作为诱导剂的IPTG相比，乳糖诱导的MPH的表达产量提高了2倍。此外，发现通过将诱导温度降低至22℃，MPH的比活性增加了48％。在22℃下添加25mM乳糖，发酵液的MPH活性具有1.4×10（4）。 ）U / mg蛋白。质粒在经修饰的培养基中没有显着减少。MPH的最佳pH和温度分别为8.0和30摄氏度。在5个月的时间里，干燥的细胞显示出解毒酶的活性没有显着降低。50 mM柠檬酸-磷酸盐缓冲液（pH 8。0）能够降解喷洒在甘蓝上的约98％的有机磷酸盐农药。排毒效率优于水，洗涤剂和市售酶产品的处理效率。另外，经酶提取物处理产生的农药水解产物被确定为实际上无毒。