Taking the green fluorescence out of the protein: dynamics of the isolated GFP chromophore anion
Taking the green fluorescence out of the protein: dynamics of the isolated GFP chromophore anion
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DOI：
10.1039/c2sc21737f
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发表时间：
2013-01-01
期刊：
影响因子：
8.4
通讯作者：
Verlet, Jan R. R.
中科院分区：
文献类型：
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作者：
Mooney, Ciaran R. S.;Horke, Daniel A.;Verlet, Jan R. R.
绿色荧光蛋白 (GFP) 由于其出色的荧光特性而被广泛用作生物学和生命科学中的标记物。在这里，我们采用飞秒时间分辨光电子能谱来研究分离的 GFP 发色团阴离子的超快激发态动力学。激发态布居被发现呈双指数衰减，特征寿命为 330 fs 和 1.4 ps。不同的光电子光谱可以分配给每个时间尺度，并指出沿衰变坐标存在瞬态中间体。在从头计算的指导下，我们将这些观察结果分配给 C-C-C 桥的扭转，然后内部转换为阴离子基态。尽管两种介质之间的吸收光谱存在差异，但真空中的动力学与在溶液中观察到的动力学非常相似。这与限制 C-C-C 键旋转的蛋白质环境一致，以防止超快内部转换并保留荧光。
The green fluorescent protein (GFP) is employed extensively as a marker in biology and the life sciences as a result of its spectacular fluorescence properties. Here, we employ femtosecond time-resolved photoelectron spectroscopy to investigate the ultrafast excited state dynamics of the isolated GFP chromophore anion. Excited state population is found to decay bi-exponentially, with characteristic lifetimes of 330 fs and 1.4 ps. Distinct photoelectron spectra can be assigned to each of these timescales and point to the presence of a transient intermediate along the decay coordinate. Guided by ab initio calculations, we assign these observations to twisting about the C-C-C bridge followed by internal conversion to the anion ground state. The dynamics in vacuo are very similar to those observed in solution, despite the difference in absorption spectra between the two media. This is consistent with the protein environment restricting rotation about the C-C-C bond in order to prevent ultrafast internal conversion and preserve the fluorescence.