Reddy Christopher M, Xu Li, Drenzek Nicholas J, Sturchio Neil C, Heraty Linnea J, Kimblin Clare, Butler Alison
Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.
J Am Chem Soc. 2002 Dec 11;124(49):14526-7. doi: 10.1021/ja0284097.
Several chlorinated organic compounds (COCs) that have been detected in a wide range of human, animal, and environmental samples may be derived from natural or anthropogenic sources. To determine whether the Cl isotope ratios of these compounds could be used to differentiate sources, we investigated the chlorine isotope effect for enzyme-catalyzed chlorination. Two aromatic substrates, 1,3,5-trimethylbenzene (TMB) and 3,5-dimethylphenol (DMP), were treated with a chloroperoxidase isolated from the fungus Caldariomyces fumago. A kinetic isotope effect (KIE) (in terms of k35/k37) was calculated to be 1.012 for TMB and 1.011 for DMP. A similar reaction, but not catalyzed, with hypochlorite yielded a much smaller KIE. These results indicate that a substantial KIE exists for this process. Furthermore, natural COCs synthesized by this enzymatic pathway may have Cl isotope ratios that will be easily distinguished from anthropogenic COCs.
在广泛的人类、动物和环境样本中检测到的几种氯化有机化合物（COC）可能来源于天然或人为来源。为了确定这些化合物的氯同位素比率是否可用于区分来源，我们研究了酶催化氯化反应的氯同位素效应。用从真菌烟曲霉中分离出的氯过氧化物酶处理两种芳香族底物，即1,3,5-三甲基苯（TMB）和3,5-二甲基苯酚（DMP）。计算得出TMB的动力学同位素效应（KIE）（以k35/k37表示）为1.012，DMP为1.011。与次氯酸盐发生的类似反应（但无催化作用）产生的KIE要小得多。这些结果表明该过程存在显著的KIE。此外，通过这种酶促途径合成的天然COC可能具有易于与人为COC区分的氯同位素比率。
