金鱼藻过氧化物酶降解双酚A的特性

本文对金鱼藻（Ceratophyllum demersum）过氧化物酶（POD）进行了分离纯化及酶学特性分析，并探讨了其对双酚A （BPA）的降解特性.结果表明，采用硫酸铵和AKTA蛋白纯化系统获得纯化的POD，该酶具有较广的温度和pH值适应范围，在温度为70℃，pH值为7，H₂O₂浓度为5mmol/L时POD酶活力最大.金鱼藻POD可高效降解BPA.当金鱼藻POD活力为10U/mL时，15min内对0.02mmol/L BPA的降解率达到99.67%，活力为25U/mL及以上时，完全降解.降解条件的最适范围分别为H₂O₂ 1~5mmol/L、30~60℃、pH 5~7.其降解动力学米氏K_m为0.09mmol/L，最大反应速度为9.71mmol/（L·h）.BPA经金鱼藻POD降解后无雌激素效应.金鱼藻POD高稳定性和高活性的特点以及对BPA的高效降解能力是该水生植物成为水环境BPA污染的理想修复工具的重要原因.

Properties of peroxidase from Ceratophyllum demersum in degradation of Bisphenol A

Peroxidase (POD) from Ceratophyllum demersum was isolated, purified and characterized, and the degradation of bisphenol A (BPA) by this POD was investigated. POD from C.demersum was purified by ammonium sulfate precipitation and AKTA protein purification system. The POD maintained relative high activity at a wide range of temperature and pH, and the highest relative activity was at 70℃, pH 7 with 5 mmol/L of H₂O₂. When the POD was 10U/mL, 99.67% degradation rate of 0.02mmol/L BPA was achieved within 15min, and BPA was completely degraded when the activity was 25U/mL and above. The optimal range of degradation conditions were at 30~60℃ and pH 5~7 with 1~5mmol/L of H₂O₂. The kinetics of enzymatic degradation was analysed under the optimal conditions. The K_m value was 0.09 mmol/L and the maximum reaction rate was 9.71mmol/(L·h). After degradation by C.demersum POD, the BPA contaminated water showed no significant estrogen effect on zebra fish. Our results indicated that POD from C.demersum was not only high stable but also efficient in the degradation of BPA, which may explain why C.demersum can be an ideal tool for BPA phytoremediation in aquatic environment.