Characterization of radicals in anaerobic degradation of benzoate, acytelene, and glycol ethers

在发酵细菌和硫酸盐还原细菌中，苯甲酰辅酶A的还原转化由与硝酸盐还原细菌中观察到的酶系统不同的酶系统催化。该反应导致环己烯羧基-CoA，并且似乎是ATP非依赖性的。提出第一步形成自由基羰基衍生物，随后还原为环己烯羧基-CoA。第二个项目涉及乙二醇醚的发酵降解，这应该是通过类似于二醇脱氢酶催化的反应的自由基机制进行的。在第三个项目中，将研究含蝶呤的乙炔水合酶形成蝶呤中心自由基及其在催化中的作用。显然，在所有情况下，蛋白质和底物为中心的自由基将通过EPR/ENDOR光谱采用快速淬灭和自旋捕获技术来鉴定。

In fermenting and sulfate-reducing bacteria, the reductive transformation of benzoyl-CoA is catalyzed by an enzyme system different from that observed in nitrate-reducing bacteria. The reaction leads to cyclohexene carboxyl-CoA, and appears to be ATP-independent. Formation of a radical carbonyl derivative is proposed for the first step which is subsequently reduced to cyclohexene carboxyl-CoA. A second project deals with the fermentative degradation of ethylene glycol ethers which is supposed to proceed via a radical mechanism analogous to the reaction catalyzed by diol dehydratases. In a third project, the molybdopterin-containing enzyme acetylene hydratase will be investigated with respect to the formation of a pterin-centered radical and its role in catalysis. Clearly, in all cases protein and substrate centered radicals will be identified by EPR/ENDOR spectroscopy employing both rapid quench and spin trap techniques.