State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China.
Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection of the People's Republic of China, Nanjing 210042, PR China.
J Hazard Mater. 2017 Jun 5;331:123-131. doi: 10.1016/j.jhazmat.2017.02.033. Epub 2017 Feb 22.
A growing body of research indicated that natural processes such as photolysis, biotransformation and sorption contribute to natural attenuation of organic compounds in natural waters. Here we report another potential natural reaction involving induction by extracellular peroxidase (POD) in sunlit humic waters. The degradation behavior of a natural estrogen 17β-estradiol (E2) in waters containing both horseradish peroxidase (HRP) and Suwannee River humic acid (SRHA) were studied under simulated sunlight. Significant enhancement of E2 degradation was observed in the presence of HRP as compared to direct and SRHA-inducted photolysis, resulting from the efficient degradation of E2 induced by HRP using photoproduced HO. The contribution of direct photolysis, indirect photolysis and enzymatic degradation to E2 degradation was calculated as 36.6, 31.7 and 31.7%, respectively. Lower yields of hydroxylation products and several new dimer products in E2+SRHA+HRP system relative to E2+SRHA system indicated that E2 degradation was primarily mediated by HRP, revealing the presence of HRP strongly affected the degradation pathway of E2. Take naturally occurring POD into consideration, enzymatic degradation may be an important attenuation pathway of E2 and other contaminants that are sensitive to peroxidases in certain waters such as humic rich freshwater system.
越来越多的研究表明，天然过程如光解、生物转化和吸附有助于天然水中有机化合物的自然衰减。在这里，我们报告了另一种涉及细胞外过氧化物酶（POD）诱导的潜在天然反应，该反应涉及在阳光照射的腐殖水中。在模拟阳光条件下，研究了含有辣根过氧化物酶（HRP）和苏湾河腐殖酸（SRHA）的水中天然雌激素 17β-雌二醇（E2）的降解行为。与直接和 SRHA 诱导的光解相比，在 HRP 存在下观察到 E2 降解的显著增强，这是由于 HRP 利用光产生的 HO 有效降解了 E2。直接光解、间接光解和酶促降解对 E2 降解的贡献分别计算为 36.6%、31.7%和 31.7%。在 E2+SRHA+HRP 体系中，羟基化产物和几个新的二聚体产物的产率较低，而在 E2+SRHA 体系中则较高，这表明 E2 的降解主要是由 HRP 介导的，这表明 HRP 的存在强烈影响了 E2 的降解途径。考虑到天然存在的 POD，酶促降解可能是 E2 和其他在某些水中对过氧化物酶敏感的污染物的重要衰减途径，如富含腐殖质的淡水系统。
