Anaerobic Dehalogenation of Chloroanilines by Dehalococcoides mccartyi Strain CBDB1 and Dehalobacter Strain 14DCB1 via Different Pathways as Related to Molecular Electronic Structure.
Anaerobic Dehalogenation of Chloroanilines by Dehalococcoides mccartyi Strain CBDB1 and Dehalobacter Strain 14DCB1 via Different Pathways as Related to Molecular Electronic Structure.
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DOI：
10.1021/acs.est.6b05730
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发表时间：
2017-03
影响因子：
11.4
通讯作者：
Shangwei Zhang;Dominik Wondrousch;Myriel Cooper;S. Zinder;G. Schüürmann;L. Adrian
中科院分区：
文献类型：
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作者：
Shangwei Zhang;Dominik Wondrousch;Myriel Cooper;S. Zinder;G. Schüürmann;L. Adrian
Mccartyi脱卤球菌菌株CBDB 1和Dehalococcoides菌株14 DCB 1分别是绿黄菌门和厚壁菌门的有机卤化物呼吸微生物。在这里，我们报告的氯代苯胺这两种细菌菌株通过不同的脱卤途径和量子化学计算的净原子电荷的基板Cl，H，和C原子的潜在机制进行了讨论。菌株CBDB1优先去除两侧为两个Cl或一个Cl和NH2的Cl，而菌株14DCB 1优先脱氯具有邻位H的Cl。对于CBDB1介导的脱氯，与Hirshfeld电荷的比较分析表明，在15种情况下，最小负Cl在14种情况下将活性底物与非活性底物区分开，并且可能代表通过cob（I）alamin的主要攻击的优选位点。对于后一种趋势，七种活性底物中有三种提供了强有力的证据，其余四种底物中有三种提供了部分支持。关于菌株14DCB 1，最正的碳连接的H原子在15种情况中的14种中再次区分活性氯苯胺和非活性氯苯胺。在这里，区域选择性是由最积极的H连接到最高的电荷（最积极或最负）携带的氯芳族C被删除的11个活性基板的10。这些发现表明，芳环H作为通过超亲核试剂Co（I）攻击的主要位点，将初始H键转化为完整的电子转移作为还原脱卤的开始。对于这两种机制，一个和两个电子转移到Cl（菌株CBDB1）或H（菌株14DCB 1）与目前可用的数据是兼容的。计算化学对反应中间体和途径的研究可能有助于在分子水平上进一步理解细菌还原脱卤。
Dehalococcoides mccartyi strain CBDB1 and Dehalobacter strain 14DCB1 are organohalide-respiring microbes of the phyla Chloroflexi and Firmicutes, respectively. Here, we report the transformation of chloroanilines by these two bacterial strains via dissimilar dehalogenation pathways and discuss the underlying mechanism with quantum chemically calculated net atomic charges of the substrate Cl, H, and C atoms. Strain CBDB1 preferentially removed Cl doubly flanked by two Cl or by one Cl and NH2, whereas strain 14DCB1 preferentially dechlorinated Cl that has an ortho H. For the CBDB1-mediated dechlorination, comparative analysis with Hirshfeld charges shows that the least-negative Cl discriminates active from nonactive substrates in 14 out of 15 cases and may represent the preferred site of primary attack through cob(I)alamin. For the latter trend, three of seven active substrates provide strong evidence, with partial support from three of the remaining four substrates. Regarding strain 14DCB1, the most positive carbon-attached H atom discriminates active from nonactive chloroanilines in again 14 out of 15 cases. Here, regioselectivity is governed for 10 of the 11 active substrates by the most positive H attached to the highest-charge (most positive or least negative) aromatic C carrying the Cl to be removed. These findings suggest the aromatic ring H as primary site of attack through the supernucleophile Co(I), converting an initial H bond to a full electron transfer as start of the reductive dehalogenation. For both mechanisms, one- and two-electron transfer to Cl (strain CBDB1) or H (strain 14DCB1) are compatible with the presently available data. Computational chemistry research into reaction intermediates and pathways may further aid in understanding the bacterial reductive dehalogenation at the molecular level.