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

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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.