[FeFe]-hydrogenase oxygen inactivation is initiated at the H cluster 2Fe subcluster.
[FeFe]-hydrogenase oxygen inactivation is initiated at the H cluster 2Fe subcluster.
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DOI：
10.1021/ja510169s
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发表时间：
2015-01
影响因子：
15
通讯作者：
K. D. Swanson;Michael W. Ratzloff;David W. Mulder;Jacob H. Artz;Shourjo Ghose;A. Hoffman;S. White
中科院分区：
文献类型：
--
作者：
K. D. Swanson;Michael W. Ratzloff;David W. Mulder;Jacob H. Artz;Shourjo Ghose;A. Hoffman;S. White
[FeFe]-氢酶催化位H簇是一种对氧(O2)敏感的复杂的铁硫辅因子。氧气的敏感性是在水分解、充氧系统中作为能源生产氢气的一个重要障碍。氧直接与H簇反应，导致酶迅速失活并最终降解。为了研究依赖O2的[FeFe]-氢酶失活的过程和H簇的降解过程，将绿藻Chlamydomonas rehardtii的高对O2敏感的[FeFe]-氢酶HydA1暴露在一定浓度的O2中，同时监测H簇光谱性质的丧失和伴随的变化。结果表明，H簇的降解是通过一系列反应进行的，其程度取决于初始的酶还原/氧化状态。降解过程开始于O2与2Fe亚团簇相互作用和反应，导致2Fe亚团簇的退化，并留下不活跃的[4Fe-4S]亚团簇状态。这种最终的失活降解产物在体外可以通过2FE亚簇成熟机，特别是HydF(EG)孵育而被重新激活，这是通过酶活性的恢复来观察的。
The [FeFe]-hydrogenase catalytic site H cluster is a complex iron sulfur cofactor that is sensitive to oxygen (O2). The O2 sensitivity is a significant barrier for production of hydrogen as an energy source in water-splitting, oxygenic systems. Oxygen reacts directly with the H cluster, which results in rapid enzyme inactivation and eventual degradation. To investigate the progression of O2-dependent [FeFe]-hydrogenase inactivation and the process of H cluster degradation, the highly O2-sensitive [FeFe]-hydrogenase HydA1 from the green algae Chlamydomonas reinhardtii was exposed to defined concentrations of O2 while monitoring the loss of activity and accompanying changes in H cluster spectroscopic properties. The results indicate that H cluster degradation proceeds through a series of reactions, the extent of which depend on the initial enzyme reduction/oxidation state. The degradation process begins with O2 interacting and reacting with the 2Fe subcluster, leading to degradation of the 2Fe subcluster and leaving an inactive [4Fe-4S] subcluster state. This final inactive degradation product could be reactivated in vitro by incubation with 2Fe subcluster maturation machinery, specifically HydF(EG), which was observed by recovery of enzyme activity.