Transformation and Removal of Tetrabromobisphenol A from Water in the Presence of Natural Organic Matter via Laccase-Catalyzed Reactions: Reaction Rates, Products, and Pathways
Transformation and Removal of Tetrabromobisphenol A from Water in the Presence of Natural Organic Matter via Laccase-Catalyzed Reactions: Reaction Rates, Products, and Pathways
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在天然有机物存在下通过漆酶催化反应从水中转化和去除四溴双酚 A：反应速率、产物和途径
DOI：
10.1021/es302680c
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发表时间：
2013-01-15
影响因子：
11.4
通讯作者：
Mao, Liang
中科院分区：
文献类型：
--
作者：
Feng, Yiping;Colosi, Lisa M.;Mao, Liang
溴化阻燃剂四溴双酚A（TBBPA）的广泛存在使其成为一个可能的关注来源。我们的实验表明，TBBPA可以有效地转化天然存在的漆酶从变色栓菌。这些反应遵循二级动力学，表观去除率是底物和酶浓度的函数。对于在不同初始浓度和有或没有天然有机物（NOM）的反应，反应产物使用液相或气相色谱质谱法进行鉴定。提出了详细的反应途径。据推测，由漆酶介导的反应产生的两个TBBPA基团通过一个基团上的氧原子和另一个基团上的丙基取代的芳族碳原子的相互作用偶联在一起。然后从自由基二聚体中消除2，6-二溴-4-异丙基苯酚碳阳离子。除了一个之外，所有检测到的产物都是由2，6-二溴-4-异丙基苯酚碳正离子的取代或质子消除引起的。在NOM的存在下，三个额外的产品被确定为反应，这表明NOM和TBBPA自由基之间发生的反应。来自水蚤的急性固定试验的数据证实，漆酶催化的TBBPA去除有效地消除了TBBPA毒性。这些发现有助于理解漆酶介导的TBBPA反应，并最终导致开发新的方法来控制TBBPA污染。
The widespread occurrence of the brominated flame retardant tetrabromobisphenol A (TBBPA) makes it a possible source of concern. Our experiments suggest that TBBPA can be effectively transformed by the naturally occurring laccase enzyme from Trametes versicolor. These reactions follow second-order kinetics, whereby apparent removal rate is a function of both substrate and enzyme concentrations. For reactions at different initial concentrations and with or without natural organic matter (NOM), reaction products are identified using liquid or gas chromatography with mass spectrometry. Detailed reaction pathways are proposed. It is postulated that two TBBPA radicals resulting from a laccase-mediated reaction are coupled together via interaction of an oxygen atom on one radical and a propyl-substituted aromatic carbon atom on the other. A 2,6-dibromo-4-isopropylphenol carbocation is then eliminated from the radical dimer. All but one of the detected products arise from either substitution or proton elimination of the 2,6-dibromo-4-isopropylphenol carbocation. Three additional products are identified for reactions in the presence of NOM, which suggests that reaction occurs between NOM and TBBPA radical. Data from acute immobilization tests with Daphnia confirm that TBBPA toxicity is effectively eliminated by laccase-catalyzed TBBPA removal. These findings are useful for understanding laccase-mediated TBBPA reactions and could eventually lead to development of novel methods to control TBBPA contamination.