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首页> 外文期刊>Environmental Science & Technology >Isotope Effects of Enzymatic Dioxygenation of Nitrobenzene and 2-Nitrotoluene by Nitrobenzene Dioxygenase
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Isotope Effects of Enzymatic Dioxygenation of Nitrobenzene and 2-Nitrotoluene by Nitrobenzene Dioxygenase

机译：硝基苯双加氧酶催化硝基苯和2-硝基甲苯的双氧同位素作用

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摘要

Oxygenation of aromatic rings is a frequent initial step in the biodegradation of persistent contaminants, and the accompanying isotope fractionation is increasingly used to assess the extent of transformation in the environment. Here, we systematically investigated the dioxygenation of two nitroaromatic compounds (nitrobenzene and 2-nitrotoluene) by nitrobenzene dioxygenase (NBDO) to obtain insights into the factors governing its C, H, and N isotope fractionation. Experiments were carried out at different levels of biological complexity from whole bacterial cells to pure enzyme. C, H, and N isotope enrichment factors and kinetic isotope effects (KIEs) were derived from the compound-specific isotope analysis of nitroarenes, whereas C isotope fractionation was also quantified in the oxygenated reaction products. Dioxygenation of nitrobenzene to catechol and 2-nitrotoluene to 3-methylcatechol showed large C isotope enrichment factors, ε_C, of -4.1 ± 0.2‰ and -2.S ± 0.2‰, respectively, and was observed consistently in the substrates and dioxygenation products. ε_H~- and ε_N-values were smaller, that is -5.7 + 13‰ and -1.0 ± 0.3‰, respectively. C isotope fractionation was also identical in experiments with whole bacterial cells and pure enzymes. The corresponding ~(13)C-KIEs for the dioxygenation of nitrobenzene and 2-nitrotoluene were 1.025 ± 0.001 and 1.018 ± 0.001 and suggest a moderate substrate specificity. Our study illustrates that dioxygenation of nitroaromatic contaminants exhibits a large C isotope fractionation, which is not masked by substrate transport and uptake processes and larger than dioxygenation of other aromatic hydrocarbons.
机译：在持久性污染物的生物降解中，芳环的氧化是一个常见的初始步骤，伴随而来的同位素分馏被越来越多地用于评估环境中的转化程度。在这里，我们系统地研究了硝基苯双加氧酶（NBDO）对两种硝基芳族化合物（硝基苯和2-硝基甲苯）的加氧作用，以了解控制其C，H和N同位素分级分离的因素。从整个细菌细胞到纯酶，都在不同的生物学复杂性水平上进行了实验。 C，H和N同位素富集因子和动力学同位素效应（KIEs）来自硝基芳烃的化合物特定同位素分析，而C同位素分馏也可在氧化反应产物中进行定量。硝基苯加氧成邻苯二酚和2-硝基甲苯加氧成3-甲基邻苯二酚显示出较大的C同位素富集因子ε_C，分别为-4.1±0.2‰和-2.S±0.2‰，并在底物和双加氧产物中一致地观察到。 ε_H〜-和ε_N值较小，分别为-5.7 + 13‰和-1.0±0.3‰。在整个细菌细胞和纯酶的实验中，C同位素分级也相同。硝基苯和2-硝基甲苯双加氧反应对应的〜（13）C-KIEs为1.025±0.001和1.018±0.001，表明底物特异性中等。我们的研究表明，硝基芳族污染物的双加氧表现出较大的C同位素分馏，这并没有被底物的运输和吸收过程所掩盖，并且比其他芳族烃的双加氧更大。

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  • 来源
    《Environmental Science & Technology》 |2014年第18期|10750-10759|共10页
  • 作者

    Sarah G. Pati; Hans-Peter E. Kohler; Jakov Bolotin; Rebecca E. Parales; Thomas B. Hofstetter;

  • 作者单位

    Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Duebendorf, Switzerland,Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zuerich, 8092 Zuerich, Switzerland;

    Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Duebendorf, Switzerland;

    Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Duebendorf, Switzerland;

    Department of Microbiology, University of California, Davis, California 95616, United States;

    Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Duebendorf, Switzerland,Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zuerich, 8092 Zuerich, Switzerland;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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