Direct Measurement of Electron Transfer Distance Decay Constants of Single Redox Proteins by Electrochemical Tunneling Spectroscopy
Direct Measurement of Electron Transfer Distance Decay Constants of Single Redox Proteins by Electrochemical Tunneling Spectroscopy
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DOI：
10.1021/nn103236e
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发表时间：
2011-03-01
期刊：
影响因子：
17.1
通讯作者：
Gorostiza, Pau
中科院分区：
文献类型：
--
作者：
Artes, Juan M.;Diez-Perez, Ismael;Gorostiza, Pau
我们提出了一种在单分子水平上直接测量距离衰减常数的方法，该常数表征氧化还原蛋白中电子转移（ET）的速率。使用双恒电位控制下的电化学隧道显微镜，我们获得了以明确的分子方向限制在纳米隧道间隙内的单个氧化还原蛋白的电流-距离光谱记录。隧道电流呈指数衰减，相应的衰减常数 (beta) 强烈支持两步隧道 ET 机制。衰减常数测量的统计分析揭示了还原态和氧化态之间的差异，这可能与酶和生物电子传递链中 ET 速率的控制有关。
We present a method to measure directly and at the single-molecule level the distance decay constant that characterizes the rate of electron transfer (ET) in redox proteins. Using an electrochemical tunneling microscope under bipotentiostatic control, we obtained current-distance spectroscopic recordings of individual redox proteins confined within a nanometric tunneling gap at a well-defined molecular orientation. The tunneling current decays exponentially, and the corresponding decay constant (beta) strongly supports a two-step tunneling ET mechanism. Statistical analysis of decay constant measurements reveals differences between the reduced and oxidized states that may be relevant to the control of ET rates in enzymes and biological electron transport chains.