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
复制标题
DOI：
10.1021/ja905388j
复制
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.
未来生物制氢的主要障碍是[FeFe]-氢化酶的氧敏感性，[FeFe]-氢化酶是由细菌和绿色藻类产生的高活性催化剂。在H（2）氧化和H2产生的条件下，使用CO作为互补探针，通过蛋白质膜电化学研究了三种代表性的[FeFe]-氢化酶与O2的反应。氢化酶是来自细菌脱硫菌和丙酮丁醇梭菌的DdHydAB和CaHydA以及来自绿色衣藻的CrHydA 1。失活速率取决于活性位点“H-簇”的氧化还原状态和通过蛋白质到达容纳H-簇的口袋的运输。在所有情况下，CO的反应都比O2快得多。在所提出的模型中，CaHydA显示出最缓慢的气体传输，因此失活速率对H-簇状态的依赖性很小，而DdHydAB显示出对H-簇状态的依赖性很大，并且对气体传输的有效屏障最小。因此，速率决定步骤被归因于不稳定的Fe-CO键的断裂，该反应可能是H-簇的原子和电子状态所固有的，并且对蛋白质不太敏感
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