CO dehydrogenase (CODH) from the Gram-negative bacterium Oligotropha carboxidovorans is a complex metalloenzyme from the xanthine oxidase family of molybdenum-containing enzymes, bearing a unique binuclear Mo-S-Cu active site in addition to two [2Fe-2S] clusters (FeSI and FeSII) and one equivalent of FAD. CODH catalyzes the oxidation of CO to CO2 with the concomitant introduction of reducing equivalents into the quinone pool, thus enabling the organism to utilize CO as sole source of both carbon and energy. Using a variety of EPR monitored redox titrations and spectroelectrochemistry, we report the redox potentials of CO dehydrogenase at pH 7.2 namely MoVI/V, MoV/IV, FeSI2+/+, FeSII2+/+, FAD/FADH and FADH/FADH-. These potentials are systematically higher than the corresponding potentials seen for other members of the xanthine oxidase family of Mo enzymes, and are in line with CODH utilising the higher potential quinone pool as an electron acceptor instead of pyridine nucleotides. CODH is also active when immobilised on a modified Au working electrode as demonstrated by cyclic voltammetry in the presence of CO.

中文翻译：

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Oligotropha carboxidovorans的CO脱氢酶的氧化还原和电催化性能。

革兰氏阴性细菌Oligotropha carboxidovorans的CO脱氢酶（CODH）是一种复杂的金属酶，来自含钼黄嘌呤氧化酶家族，除了两个[2Fe-2S]簇外，还具有独特的双核Mo-S-Cu活性位点（ FeSI和FeSII）和一当量的FAD。CODH催化将CO氧化为CO2，同时将还原当量引入醌库中，从而使生物体能够将CO用作碳和能量的唯一来源。使用各种EPR监测的氧化还原滴定和光谱电化学，我们报告了pH 7.2时CO脱氢酶的氧化还原电位，即MoVI / V，MoV / IV，FeSI2 + / +，FeSII2 + / +，FAD / FADH和FADH / FADH-。这些电位在系统上高于Mo酶的黄嘌呤氧化酶家族其他成员所观察到的对应电位，并且与CODH一致，后者利用较高电位的醌类库作为电子受体而不是吡啶核苷酸，从而使CODH发挥作用。当固定在修饰的Au工作电极上时，CODH也具有活性，如在CO存在下通过循环伏安法证明的那样。