蛋白质中光致异构化途径的静电控制⊙☉

    美国斯坦福大学Steven G. Boxer小组发现蛋白质中光致异构化途径的静电控制。相关论文发表在2020年1月3日出版的《科学》上。

    研究人员系统地改变了绿色荧光蛋白发色团在光开关变体Dronpa2中的静电性质，使用琥珀抑制将给电子基团和吸电子基团引入酚盐环。通过分析吸收（颜色）、荧光量子产率以及对基态和激发态异构化的能垒，研究人员定量地评估了空间和静电的贡献，并证明了静电效应是如何偏向发色团光异构化的途径的，从而产生了指导蛋白质设计的通用框架。

    据悉，光激发后围绕特定键的旋转对于光遗传学、超分辨率显微镜和光敏分子装置中的成像至关重要。控制键特异性光异构化的空间和静电效应的竞争作用已被广泛讨论，后者起因于激发时生色团电荷的转移。

    附：英文原文

    Title: Electrostatic control of photoisomerization pathways in proteins

    Author: Matthew G. Romei, Chi-Yun Lin, Irimpan I. Mathews, Steven G. Boxer

    Issue&Volume: 2020/01/03

    Abstract: Rotation around a specific bond after photoexcitation is central to vision and emerging opportunities in optogenetics, super-resolution microscopy, and photoactive molecular devices. Competing roles for steric and electrostatic effects that govern bond-specific photoisomerization have been widely discussed, the latter originating from chromophore charge transfer upon excitation. We systematically altered the electrostatic properties of the green fluorescent protein chromophore in a photoswitchable variant, Dronpa2, using amber suppression to introduce electron-donating and electron-withdrawing groups to the phenolate ring. Through analysis of the absorption (color), fluorescence quantum yield, and energy barriers to ground- and excited-state isomerization, we evaluate the contributions of sterics and electrostatics quantitatively and demonstrate how electrostatic effects bias the pathway of chromophore photoisomerization, leading to a generalized framework to guide protein design.

    DOI: 10.1126/science.aax1898

    Source: https://science.sciencemag.org/content/367/6473/76

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