Single electron transfer events and dynamical heterogeneity in the small protein azurin from Pseudomonas aeruginosa,Chemical Science

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Single electron transfer events and dynamical heterogeneity in the small protein azurin from Pseudomonas aeruginosa
Chemical Science ( IF 7.6 ) Pub Date : 2019-11-27 , DOI: 10.1039/c9sc05405g
Biswajit Pradhan ₁ , Christopher Engelhard ₁ , Sebastiaan Van Mulken ₁ , Xueyan Miao ₂ , Gerard W Canters ₁ , Michel Orrit ₁

Affiliation

Monitoring the fluorescence of single-dye-labeled azurin molecules, we observed the reaction of azurin with hexacyanoferrate under controlled redox potential yielding data on the timing of individual (forward and backward) electron transfer (ET) events. Change-point analysis of the time traces demonstrates significant fluctuations of ET rates and of mid-point potential E₀. These fluctuations are a signature of dynamical heterogeneity, here observed on a 14 kDa protein, the smallest to date. By correlating changes in forward and backward reaction rates we found that 6% of the observed change events could be explained by a change in midpoint potential, while for 25% a change of the donor–acceptor coupling could explain the data. The remaining 69% are driven by variations in complex association constants or structural changes that cause forward and back ET rates to vary independently. Thus, the observed spread in individual ET rates could be related in a unique way to variations in molecular parameters. The relevance for the understanding of metabolic processes is briefly discussed.

中文翻译：

铜绿假单胞菌小蛋白天青蛋白的单电子转移事件和动力学异质性

通过监测单染料标记的天青蛋白分子的荧光，我们观察了天青蛋白与六氰基高铁酸盐在受控氧化还原电位下的反应，产生了有关单个（向前和向后）电子转移（ET）事件的时间的数据。时间轨迹的变化点分析表明 ET 速率和中点电位E ₀存在显着波动。这些波动是动态异质性的标志，这里是在 14 kDa 蛋白质上观察到的，这是迄今为止最小的蛋白质。通过关联正向和反向反应速率的变化，我们发现观察到的变化事件中有 6% 可以通过中点电位的变化来解释，而 25% 的变化事件可以通过供体-受体耦合的变化来解释数据。其余 69% 是由复杂关联常数的变化或导致前向和后向 ET 率独立变化的结构变化驱动的。因此，观察到的个体 ET 率的分布可能以一种独特的方式与分子参数的变化相关。简要讨论了理解代谢过程的相关性。

更新日期：2019-11-27

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