揭示绿色荧光蛋白 (GFP) 发色团类似物中双荧光的机制途径：详细的理论研究,The Journal of Physical Chemistry B

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揭示绿色荧光蛋白 (GFP) 发色团类似物中双荧光的机制途径：详细的理论研究
The Journal of Physical Chemistry B ( IF 2.8 ) Pub Date : 2022-11-10 , DOI: 10.1021/acs.jpcb.2c03842
Bittu Lama ₁ , Manabendra Sarma ₁

Affiliation

具有质子供体和接受位点的绿色荧光蛋白 (GFP) 发色团的对磺酰胺 (p-TsABDI) 类似物的光物理特性已在极性溶剂中被利用，以了解发色团不寻常的双荧光性质的起源。在极性溶剂中，该化合物在光激发时发生结构重排，导致 S _{1处的超快激发态分子间质子转移 (ESIPT) 现象}表面。在这项工作中，我们采用静态电子结构计算和动态分子动力学模拟来揭示 p-TsABDI 类似物在极性溶剂中的这种特殊行为的根本原因。为了充分表示这一点并提供有关溶剂分子介导的 ESIPT 机制的广泛信息，我们使用可极化连续体 (IEFPCM) 模型的积分方程形式主义变体考虑了显式溶剂分子。从静态计算分析，我们可以得出结论，化合物的双发射行为归因于激发态的质子转移（PT）现象。然而，仅基于静态计算，很难确定 PT 现象的机理路径。因此，为了研究 ESIPT 过程的动力学和反应机制，我们对溶剂簇中的 p-TsABDI 进行了即时动力学模拟。动力学模拟结果表明，基于所有质子转移过程之间的时间滞后，ESIPT 机制以逐步的方式从生色团的亚苄基部分到其咪唑啉酮部分发生。然而，S 之间不存在交叉点₁ - 和 S ₀ -状态证实了反应的 PT 特征。

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Unraveling the Mechanistic Pathway for the Dual Fluorescence in Green Fluorescent Protein (GFP) Chromophore Analogue: A Detailed Theoretical Investigation

The photophysical properties of the para-sulfonamide (p-TsABDI) analogue of the green fluorescent protein (GFP) chromophore with both proton donating and accepting sites have been exploited in polar solvents to understand the origin of the unusual dual fluorescence nature of the chromophore. In the polar solvents, the compound undergoes structural rearrangement upon photoexcitation, leading to the ultrafast excited-state intermolecular proton transfer (ESIPT) phenomenon at the S₁ surface. In this work, we employed both the static electronic structure calculations and on-the-fly molecular dynamics simulation to unravel the underlying reason for this peculiar behavior of the p-TsABDI analogue in polar solvents. To represent this adequately and provide extensive information on the ESIPT mechanism mediated by the solvent molecules, we considered explicit solvent molecules using the integral equation formalism variant of polarizable continuum (IEFPCM) model. From the static calculation analysis, we can conclude that the dual emissive behavior of the compound is ascribed to the proton transfer (PT) phenomena in the excited-state. However, based on the static calculation exclusively, it is hard to ascertain the mechanistic pathway of the PT phenomena. Hence, to investigate the dynamics and reaction mechanism for the ESIPT process, we performed the on-the-fly dynamics simulation for p-TsABDI in solvent clusters. Dynamics simulation results reveal that, based on the time lag between all the proton transfer processes, the ESIPT mechanism occurs in a stepwise manner from the benzylidene moiety of the chromophore to its imidazolinone moiety. However, the nonexistence of crossings between the S₁- and S₀-states confirms the PT characteristics of the reactions.

更新日期：2022-11-10

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