Biochemistry of the Anaerobic Dehalogenation of Chlorinated Aromatics

Ragsdale EPA列出的20种最危险的化合物包括10种卤代有机化合物。厌氧生物可能在此类化合物的自然生物降解过程中发挥非常重要的作用，并有望对受卤代化合物污染的场地进行生物修复。已经有研究表明，可以代谢多氯联苯（PCB），杀虫剂和除草剂的财团。最近发现的脱硫菌或脱硫菌类的成员可以在称为脱卤呼吸的能量产生过程中快速有效地去除烷基卤化物和芳基卤化物的卤素基团。这是一种还原脱卤反应，其中电子供体（丙酮酸盐、H2等）通过电子转移链还原烷基或芳基卤化物，有效地用氢化物等价物取代氯化物。这是对这种生物和相关酶的研究的早期阶段。本项目旨在更好地了解脱卤芳烃的还原脱卤过程。到目前为止，已经分离出几种脱卤呼吸生物。两个芳基氯脱卤酶已被纯化，其中一个编码基因已被克隆。对这种酶的机理研究很少。这里概述的研究将提供关于这类相对较新的酶促反应的新信息。将对编码脱卤酶的基因进行克隆、测序和过表达。 将对脱卤酶进行表征，并阐明还原脱卤机制。这些酶似乎含有血红素或维生素B12。这代表了这些金属中心的新作用，这将被阐明。 将进行光谱和电化学研究，以确定和确定这些辅基在脱卤过程中的作用。这些研究可能会产生重大的生物技术影响。这些生物体或来自这些生物体的酶可用于生物修复过程。本文所述的研究旨在确定哪些生物体以及这些生物体中的哪些酶最有可能对受多氯联苯污染的场地进行生物修复，并用于植物生物技术。生物体和纯化的酶的活性将针对其在芳环的邻位、Meta位和帕拉脱卤的能力以及还原性脱卤异生物质如多氯联苯和除草剂如麦草畏和2，4-D的能力进行评估。

RagsdaleThe EPA list of the twenty most hazardous compounds includes ten halogenated organic compounds. Anaerobic organisms are likely to be very important in the natural biodegradation of such compounds and show promise for bioremediation of sites contaminated with halogenated compounds. There have been studies of consortia that can metabolize polychlorinated biphenyls (PCBs), pesticides, and herbicides. Members of the recently discovered Desulfitobacterium or Desulfomonile class can rapidly and efficiently remove the halogen group of alkyl halides and aryl halides in an energy yielding process called dehalorespiration. This is a reductive dehalogenation in which an electron donor (pyruvate, H2, etc.) reduces the alkyl or aryl halide through an electron transfer chain, effectively replacing the chloride with a hydride equivalent. This is an early stage in research on such organisms and the relevant enzymes. This project is aimed at better understanding the process of reductive dehalogenation of dehalogenated aromatics. So far several dehalorespiring organisms have been isolated. Two aryl chloride dehalogenases have been purified and the gene encoding one of these has been cloned. There have been few mechanistic studies of such enzymes. The research outlined here will provide new information about this relatively new class of enzymatic reactions. The genes encoding the dehalogenase(s) will be cloned, sequenced and overexpressed. The dehalogenase(s) will be characterized and the reductive dehalogenation mechanism(s) will be elucidated. The enzymes appear to contain either heme or vitamin B12. This represents a new role for these metal centers, which will be elucidated. Spectroscopic and electrochemical studies will be performed to identify and determine the roles of these prosthetic groups in the dehalogenation process. There could be significant biotechnological impact of these studies. The organisms or enzymes from these organisms could be used in bioremediation processes. Research described here aims to determine which organisms and which enzymes from these organisms show the most potential for bioremediating sites contaminated with PCBs and for use in plant biotechnology. The activities of the organisms and purified enzymes will be assessed for their ability to dehalogenate at the ortho, meta, and para positions of the aromatic ring and to reductively dehalogenate xenobiotics like Aroclor and herbicides like dicamba and 2,4-D.