A Light-Induced Reaction with Oxygen Leads to Chromophore Decomposition and Irreversible Photobleaching in GFP-Type Proteins
A Light-Induced Reaction with Oxygen Leads to Chromophore Decomposition and Irreversible Photobleaching in GFP-Type Proteins
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DOI：
10.1021/acs.jpcb.5b02271
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发表时间：
2015-04-30
影响因子：
3.3
通讯作者：
Krylov, Anna I.
中科院分区：
文献类型：
--
作者：
Grigorenko, Bella L.;Nemukhin, Alexander V.;Krylov, Anna I.
绿色荧光蛋白（GFP）家族的蛋白质的光漂白和光稳定性对于这些广泛使用的生物标志物的实际应用是至关重要的。在模拟的基础上，我们提出了一种机制，在强光照射下的GFP型蛋白质的不可逆漂白。该机制的关键特征是发色团与蛋白质桶内的分子氧（O-2）发生光诱导反应，导致发色团分解。使用量子力学/分子力学（QM/MM）建模，我们表明，包括蛋白质结合的Chro（-）和O-2的模型系统可以被激发到分子间电荷转移（CT）特征的电子态（Chro（中心点）... O-2（-中心点））。一旦处于CT状态，该系统经历一系列具有低活化势垒的化学反应，导致酚环和咪唑啉酮环之间的桥键断裂和发色团分解。
Photobleaching and photostability of proteins of the green fluorescent protein (GFP) family are crucially important for practical applications of these widely used biomarkers. On the basis of simulations, we propose a mechanism for irreversible bleaching in GFP-type proteins under intense light illumination. The key feature of the mechanism is a photoinduced reaction of the chromophore with molecular oxygen (O-2) inside the protein barrel leading to the chromophore's decomposition. Using quantum mechanics/molecular mechanics (QM/MM) modeling we show that a model system comprising the protein-bound Chro(-) and O-2 can be excited to an electronic state of the intermolecular charge-transfer (CT) character (Chro(center dot)...O-2(-center dot)). Once in the CT state, the system undergoes a series of chemical reactions with low activation barriers resulting in the cleavage of the bridging bond between the phenolic and imidazolinone rings and disintegration of the chromophore.