Enzymatic reductions in the anaerobic aromatic at extremely low redox potentials

在极低的氧化还原电位下酶促还原厌氧芳香族化合物

• 批准号: 5454254
• 负责人: Professor Dr. Matthias Boll
• 金额: --
• 依托单位: Forschungsschwerpunkt Mikrobiologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2008-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5454254?language=en
• 关键词: Enzymatic; reductions; anaerobic; aromatic; extremely

In recent years, a number of unprecedented enzymatic reactions have been discovered in the aromatic metabolism of anaerobic bacteria. Two key enzymes of this metabolism, benzoyl-CoA reductase (BCR, dearomatizing) and 4-hydroxybenzoyl-CoA reductase (HCR, dehydroxylating), catalyze unique reductions at extremely low redox potentials in mechanisms similar to the Birch reduction in organic synthesis. BCR overcomes the high redox barrier by coupling the reductive dearomatization of benzoyl-CoA to a stoichiometrical ATP-hydrolysis. In contrast, the enzymatic dehydroxylation catalyzed by HCR is not coupled to an exergonic reaction. BCR contains three [4Fe-4S] clusters, one of which is supposed to be in special coordination with a disulfide species. HCR is an Fe-S/flavo/molybdo-protein belonging to the xanthine oxidase family. Structure/function relationships of both enzymes will be elucidated by protein crystallization/- X-Ray analysis and by a number of spectroscopic techniques. BCR and HCR will be studied in different facultative and strictly anaerobic bacteria degrading aromatic compounds. The results obtained should provide general insights into the mechanism of enzymatic redox processes at extremely low potentials.

近年来，在厌氧细菌的芳香代谢中发现了许多前所未有的酶促反应。这种代谢的两种关键酶，苯甲酰辅酶A还原酶（BCR，脱芳）和4-羟基苯甲酰辅酶A还原酶（HCR，脱羟基），在极低的氧化还原电位下催化独特的还原，其机制类似于有机合成中的Birch还原。BCR通过将苯甲酰基-CoA的还原脱芳构化与化学计量的ATP水解偶联来克服高氧化还原势垒。相比之下，由HCR催化的酶促脱羟基不与放能反应偶联。BCR含有三个[4Fe-4S]簇，其中一个应该与二硫化物物种特别配位。HCR是属于黄嘌呤氧化酶家族的Fe-S/flavo/peptido-蛋白。这两种酶的结构/功能关系将通过蛋白质结晶/X射线分析和许多光谱技术来阐明。BCR和HCR将在不同的兼性和严格厌氧细菌降解芳香族化合物进行研究。所获得的结果应提供一般的见解酶促氧化还原过程中的机制在极低的电位。