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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的耐氧加氢酶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 hyperthermophilicnbacterium Aquifex aeolicus shows increased oxygen tolerance and thermostability and can form very stablenfilms on pyrolytic graphite electrodes. Oxygen-tolerant enzymes, like the ones from A. aeolicus and Ralstonianeutropha, are reported to be insensitive to CO inhibition. This is in contrast to known and well-characterizedn(oxygen-sensitive) hydrogenases, for which carbon monoxide is a competitive inhibitor. In this study, theninteraction of Hase I from A. aeolicus with CO is examined using in situ infrared electrochemistry and time-nresolved FTIR spectroscopy. We could observe the formation of a CO adduct state, a finding that set thengrounds to investigate the affinity of an O2-tolerant enzyme for binding CO as well as the reversibility of thisnprocess. In the case of A. aeolicus, this extrinsic CO is shown to be weakly attached and the adduct state isnlight-sensitive at low temperatures. The energetic parameters for the rebinding of CO at the active site werenestimated from the rate constants of this process after photolysis and the results compared to those obtainednfor standard hydrogenases. Formation of a weak Ni-CO bond in the active site of Hase I most likely resultsnfromthe different interaction of this enzyme with inhibitors and/or different active site electronic properties tonwhich non standard amino acid residues in the vicinity of the active site might contribute.
机译：[NiFe]氢化酶（Hase I）参与嗜热嗜热菌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，如来自风杆菌和拉尔斯顿营养类似物的酶，对CO抑制不敏感。这与已知的和特征鲜明的n（氧敏感）氢化酶相反，后者的一氧化碳是竞争性抑制剂。在这项研究中，然后使用原位红外电化学和时间分辨FTIR光谱研究了水曲霉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O2的酶与一氧化碳结合的亲和力以及该过程的可逆性奠定了基础。对于A. aeoolicus而言，该外部CO表现出较弱的附着性，并且加合物在低温下对光不敏感。从光解后该过程的速率常数中确定了活性位点上CO重新结合的能量参数，并将结果与​​标准氢化酶得到的结果进行了比较。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/或不同的活性位点电子性质所致，这可能是活性位点附近的非标准氨基酸残基造成的。

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