Electron transfer with azurin at Au-SAM junctions in contact with a protic ionic melt: impact of glassy dynamics.
Electron transfer with azurin at Au-SAM junctions in contact with a protic ionic melt: impact of glassy dynamics.
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DOI：
10.1039/c3cp51896e
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发表时间：
2013-09
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影响因子：
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通讯作者：
D. Khoshtariya;T. Dolidze;T. Tretyakova;D. Waldeck;R. van Eldik
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作者：
D. Khoshtariya;T. Dolidze;T. Tretyakova;D. Waldeck;R. van Eldik
金电极涂有烷硫醇 SAM-天青蛋白（Az，蓝色铜氧还蛋白）组件，并与作为电解质的水掺杂和缓冲质子离子熔体磷酸二氢胆碱 ([ch][dhp]) 接触。应用快速扫描蛋白膜伏安法来探索接近玻璃化转变边界条件下的界面生物电子转移（ET）。研究了 ET 速率与水量、温度 (273-353 K) 和压力 (0.1-150 MPa) 的函数关系。将 Az 膜暴露于半固体电解质极大地影响了蛋白质的构象动力学，因此通过在额外复杂的动态控制方案中发生的机制，将 ET 速率与使用常规电解质的参考系统的早期研究进行比较（D. E. Khoshtariya 等人，Proc. Natl. Acad. Sci. U. S. A., 2010, 107, 2757-2762），从而允许公开甚至更不常见的机械图案。对于低含水量的样品（每 [ch][dhp] 约 3 个或更少的水），在中等低温（低于约 298 K）和/或高压（150 MPa）下，伏安曲线系统地偏离标准马库斯电流-过电压模式，这被认为是由于在玻璃形成阈值附近吉布斯能量井的基本陡峭导致线性响应近似的崩溃。含水量较高的电解质（每 [ch][dhp] 6 至 15 个水）表现出异常的温度和压力性能，表明系统跨越了一个广泛的非遍历区，该区域是由 Az 蛋白的 ET 耦合大规模构象（高度合作）模式的相互作用产生的，本质上与电解质（水掺杂的 [ch][dhp]）最慢的集体弛豫有关。
Gold electrodes were coated with alkanethiol SAM-azurin (Az, blue cupredoxin) assemblies and placed in contact with a water-doped and buffered protic ionic melt as the electrolyte, choline dihydrogen phosphate ([ch][dhp]). Fast-scan protein-film voltammetry was applied to explore interfacial biological electron transfer (ET) under conditions approaching the glass-transition border. The ET rate was studied as a function of the water amount, temperature (273-353 K), and pressure (0.1-150 MPa). Exposure of the Az films to the semi-solid electrolyte greatly affected the protein's conformational dynamics, hence the ET rate, via the mechanism occurring in the extra complicated dynamically-controlled regime, is compared to the earlier studies on the reference system with a conventional electrolyte (D. E. Khoshtariya et al., Proc. Natl. Acad. Sci. U. S. A., 2010, 107, 2757-2762), allowing for the disclosure of even more uncommon mechanistic motifs. For samples with low water content (ca. 3 or less waters per [ch][dhp]), at moderately low temperatures (below ca. 298 K) and/or high pressure (150 MPa), the voltammetric profiles systematically deviated from the standard Marcus current-overvoltage pattern, deemed as attributable to a breakdown of the linear response approximation through the essential steepening of the Gibbs energy wells near the glass-forming threshold. Electrolytes with a higher water content (6 to 15 waters per [ch][dhp]) display anomalous temperature and pressure performances, suggesting that the system crosses a broad nonergodic zone which arises from the interplay of ET-coupled large-scale conformational (highly cooperative) modes of the Az protein, inherently linked to the electrolyte's (water-doped [ch][dhp]) slowest collective relaxation(s).