Electrochemical investigations of the interconversions between catalytic and inhibited states of the [FeFe]-hydrogenase from Desulfovibrio desulfuricans.
Electrochemical investigations of the interconversions between catalytic and inhibited states of the [FeFe]-hydrogenase from Desulfovibrio desulfuricans.
复制标题
脱硫弧菌 [FeFe]-氢化酶催化状态和抑制状态之间相互转化的电化学研究。
DOI：
--
复制
发表时间：
2006
影响因子：
15
通讯作者：
F. Armstrong
中科院分区：
文献类型：
--
作者：
A. Parkin;C. Cavazza;J. Fontecilla;F. Armstrong
利用蛋白质膜伏安法在H2气氛下研究脱硫弧菌[FeFe]-加氢酶的催化性能，揭示并建立了许多其他技术无法观察到或定量测量的有趣性质。催化偏倚（固有的氧化氢与还原质子的能力）在很宽的pH范围内被量化：酶精通H2氧化（从pH bbb6开始）和H2生成（pH < 6）。产氢被H2抑制，但效果远小于从Allochromatium vinosum或Desulfovibrio fructosovorans中观察到的[NiFe]-氢化酶。在厌氧和正电位条件下，[FeFe]-氢化酶被氧化为无活性形式，对CO和O2反应惰性，在1 bar H2下单电子还原后迅速重新激活。这种相互转化的电位依赖性表明，在pK(ox) = 5.9时，氧化无活性形式存在于两种ph相互转化状态。对H2下co抑制酶的研究表明，在-109 mV（监测H2氧化）的白光下，活性的速率明显增强，而在低电位（-540 mV，监测H+还原）下则没有，从而证明了依赖于氧化态的光致性。
Studies of the catalytic properties of the [FeFe]-hydrogenase from Desulfovibrio desulfuricans by protein film voltammetry, under a H2 atmosphere, reveal and establish a variety of interesting properties not observed or measured quantitatively with other techniques. The catalytic bias (inherent ability to oxidize hydrogen vs reduce protons) is quantified over a wide pH range: the enzyme is proficient at both H2 oxidation (from pH > 6) and H2 production (pH < 6). Hydrogen production is inhibited by H2, but the effect is much smaller than observed for [NiFe]-hydrogenases from Allochromatium vinosum or Desulfovibrio fructosovorans. Under anaerobic conditions and positive potentials, the [FeFe]-hydrogenase is oxidized to an inactive form, inert toward reaction with CO and O2, that rapidly reactivates upon one-electron reduction under 1 bar of H2. The potential dependence of this interconversion shows that the oxidized inactive form exists in two pH-interconvertible states with pK(ox) = 5.9. Studies of the CO-inhibited enzyme under H2 reveals a strong enhancement of the rate of activation by white light at -109 mV (monitoring H2 oxidation) that is absent at low potential (-540 mV, monitoring H+ reduction), thus demonstrating photolability that is dependent upon the oxidation state.