Electrochemical Kinetic Investigations of the Reactions of [FeFe]-Hydrogenases with Carbon Monoxide and Oxygen: Comparing the Importance of Gas Tunnels and Active-Site Electronic/Redox Effects
Electrochemical Kinetic Investigations of the Reactions of [FeFe]-Hydrogenases with Carbon Monoxide and Oxygen: Comparing the Importance of Gas Tunnels and Active-Site Electronic/Redox Effects
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DOI：
10.1021/ja905388i
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发表时间：
2009-10-21
影响因子：
15
通讯作者：
Armstrong, Fraser A.
中科院分区：
文献类型：
--
作者：
Goldet, Gabrielle;Brandmayr, Caterina;Armstrong, Fraser A.
未来生物制氢的一个主要障碍是[FeFe]-氢酶的氧敏感性，这是细菌和绿藻产生的高活性催化剂。以CO为补充探针，在H(2)氧化和氢气生成的条件下，用蛋白质膜电化学法研究了三种具有代表性的[FeFe]-氢酶与O2的反应。氢酶是来自脱硫杆菌的DdHydAB和CaHydA，以及来自绿藻Chlamydomonas rehardtii的乙酰丁酸梭菌和CrHydA1，失活速率取决于或)活性部位‘H-簇’的氧化还原状态，并通过蛋白质运输到达H-簇所在的口袋。在所有情况下，CO的反应速度都比02快得多。在所提出的模型中，CaHydA表现出最缓慢的气体运输，因此失活率对H-团簇状态的依赖性很小，而DdHydAB显示出对H-团簇状态的很大依赖，并且对气体运输的最小有效障碍所有三种酶都显示出相似的CO抑制的再激活速率，这在光照下增加，因此，速率决定步骤被分配给不稳定的Fe-CO键的断裂，这一反应可能是H-团簇的原子和电子态所固有的，对周围的蛋白质不那么敏感
A major obstacle for future biohydrogen production is the oxygen sensitivity of [FeFe]-hydrogenases, the highly active catalysts produced by bacteria and green algae. The reactions of three representative [FeFe]-hydrogenases with 02 have been studied by protein film electrochemistry under conditions of both H(2) oxidation and H2 production, using CO as a complementary probe. The hydrogenases are DdHydAB and CaHydA from the bacteria Desulfovibno desulfuncans and Clostridium acetobutylicum and CrHydA1 from the green alga Chlamydomonas reinhardtii Rates of inactivation depend or) the redox state of the active site 'H-cluster' and on transport through the protein to reach the pocket in which the H-cluster is housed. In all cases CO reacts much faster than 02 In the model proposed, CaHydA shows the most sluggish gas transport and hence little dependence of inactivation rate on H-cluster stata, wheraas DdHydAB shows a large dependence on H-cluster state and the least effective barrier to gas transport All three enzymes show a similar rate of reactivation from CO inhibition, which increases upon illumination the rate-determining step is thus assigned to cleavage of the labile Fe-CO bond, a reaction likely to be intrinsic to the atomic and electronic state of the H-cluster and less sensitive to the surroundrig protein