A Novel Dialkylamino GFP Chromophore as an Environment-Polarity Sensor Reveals the Role of Twisted Intramolecular Charge Transfer
A Novel Dialkylamino GFP Chromophore as an Environment-Polarity Sensor Reveals the Role of Twisted Intramolecular Charge Transfer
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DOI：
10.3390/chemosensors9080234
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发表时间：
2021-08-01
期刊：
影响因子：
4.2
通讯作者：
Fang, Chong
中科院分区：
文献类型：
--
作者：
Chen, Cheng;Boulanger, Sean A.;Fang, Chong
我们发现了一种新的荧光团，通过将二甲氨基（-NMe 2）到构象锁定的绿色荧光蛋白（GFP）支架。它表现出显着的溶剂极性依赖性的荧光行为，并有可能找到广泛的应用，在体外和体内的环境极性传感器。超快飞秒瞬态吸收（fs-TA）光谱与量子计算相结合揭示了扭曲的分子内电荷转移（TICT）状态的存在下，这是由旋转的-NMe 2组的电子激发态。与亮荧光态（FS）相反，TICT态是暗的并且在形成时有效地淬灭荧光。我们采用了一种新开发的多变量分析方法，在各种溶剂中的FS寿命，并表明FS -> TICT反应势垒主要是由氢键能力，而不是溶剂的粘度调制，占所观察到的极性依赖性。这些深刻的机制的见解进一步证实了两个类似的GFP衍生的发色团，其中的旋转的-NMe 2基团被抑制的结构锁定的荧光性的显着损失。
We discovered a novel fluorophore by incorporating a dimethylamino group (-NMe2) into the conformationally locked green fluorescent protein (GFP) scaffold. It exhibited a marked solvent-polarity-dependent fluorogenic behavior and can potentially find broad applications as an environment-polarity sensor in vitro and in vivo. The ultrafast femtosecond transient absorption (fs-TA) spectroscopy in combination with quantum calculations revealed the presence of a twisted intramolecular charge transfer (TICT) state, which is formed by rotation of the -NMe2 group in the electronic excited state. In contrast to the bright fluorescent state (FS), the TICT state is dark and effectively quenches fluorescence upon formation. We employed a newly developed multivariable analysis approach to the FS lifetime in various solvents and showed that the FS -> TICT reaction barrier is mainly modulated by H-bonding capability instead of viscosity of the solvent, accounting for the observed polarity dependence. These deep mechanistic insights are further corroborated by the dramatic loss of fluorogenicity for two similar GFP-derived chromophores in which the rotation of the -NMe2 group is inhibited by structural locking.