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首页> 外文期刊>Biochemistry >The Oxygen-Tolerant Hydrogenase I from Aquifex aeolicus Weakly Interacts with Carbon Monoxide: An Electrochemical and Time-Resolved FTIR Study
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The Oxygen-Tolerant Hydrogenase I from Aquifex aeolicus Weakly Interacts with Carbon Monoxide: An Electrochemical and Time-Resolved FTIR Study

机译：来自Aquifex aeolicus的耐氧氢酶I与一氧化碳弱相互作用：电化学和时间分辨FTIR研究

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摘要

The [NiFe] hydrogenase (Hase I) involved in the aerobic respiration of the hyperthermophilic bacterium Aquifex aeolicus shows increased oxygen tolerance and thermostability and can form very stable films on pyrolytic graphite electrodes. Oxygen-tolerant enzymes, like the ones from A. aeolicus and Ralstonia eutropha, are reported to be insensitive to CO inhibition. This is in contrast to known and well-characterized ( oxygen-sensitive) hydrogenases, for which carbon monoxide is a competitive inhibitor. In this study, the interaction of Hase I from A. aeolicus with CO is examined using in situ infrared electrochemistry and timeresolved FTIR spectroscopy. We could observe the formation of a CO adduct state, a finding that set the grounds to investigate the affinity of an 02-tolerant enzyme for binding CO as well as the reversibility of this process. In the case of A. aeolicus, this extrinsic CO is shown to be weakly attached and the adduct state is light-sensitive at low temperatures. The energetic parameters for the rebinding of CO at the active site were estimated from the rate constants of this process after photolysis and the results compared to those obtained for standard hydrogenases. Formation of a weak Ni-CO bond in the active site of Hase I most likely results from the different interaction of this enzyme with inhibitors and/or different active site electronic properties to which non standard amino acid residues in the vicinity of the active site might contribute.
机译：[NiFe]氢化酶（Hase I）参与超嗜热细菌Aquifex aeolicus的有氧呼吸，显示出更高的耐氧性和热稳定性，并且可以在热解石墨电极上形成非常稳定的膜。据报道，耐氧性酶，如来自风铃草和富营养小球藻的酶，对CO抑制不敏感。这与一氧化碳是竞争性抑制剂的已知且特征明确的（对氧敏感的）氢化酶相反。在这项研究中，使用原位红外电化学和时间分辨FTIR光谱检查了水曲霉Hase I与CO的相互作用。我们可以观察到一氧化碳加合物状态的形成，这一发现为研究耐受02的酶与二氧化碳结合的亲和力以及该过程的可逆性奠定了基础。在油曲霉的情况下，该外部CO显示出弱附着，并且加合物状态在低温下对光敏感。根据光解后此过程的速率常数估算活性位点上CO重新结合的能量参数，并将结果与​​标准氢化酶的结果进行比较。在Hase I的活性位点中形成弱的Ni-CO键很可能是由于该酶与抑制剂的不同相互作用和/或活性位点附近的非标准氨基酸残基可能具有的不同活性位点电子特性引起的有助于。

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