International Collaboration in Chemistry on Control of Excited State Proton Transfer in GFP

2008年诺贝尔奖表彰了绿色荧光蛋白(GFP)和相关荧光蛋白作为监测细胞和组织中蛋白质定位和运输的工具的革命性生物学应用。然而，来自水母Aequorea Victoria的原型GFP也是独一无二的，它在吸收光子后表现出高效(&gt；80%)的质子转移。质子转移有助于大多数生物反应，但通常发生在难以直接观察的时间尺度上。因此，利用飞秒光脉冲触发质子转移的能力为理解蛋白质如何控制这一无处不在的过程提供了无与伦比的机会。我们提出的研究方案是假设驱动的，旨在了解超快激发态质子转移(ESPT)反应的动力学和控制。特别是，我们希望识别形成质子转移理论处理的基本元素的低频促进振动。我们介绍了在ESPT反应期间发生的低频振动相干的初步测量。目前，绿色荧光蛋白中ESPT的控制被广泛讨论，我们建议帮助解决一些悬而未决的问题，如反应势垒和熵，生色团冷却的作用，低频模式的识别和分配，以及蛋白质-生色团结构的异质性和相互转化。超快动力学、振动相干光谱(VCS)、瞬时可见-可见和可见光-红外吸收光谱、飞秒受激拉曼光谱(FSRs)和相干控制光谱将被用来剖析微观细节。将特别重视与温度有关的研究。包括蛋白质环境在内的高级计算化学计算的进一步发展将有助于解释光谱结果。反过来，实验结果将为计算方法提供必要的校准。

The 2008 Nobel Prize recognized the revolutionary biological applications of the green fluorescent protein (GFP) and related fluorescent proteins as tools for monitoring protein localization and trafficking in cells and tissues. However, the prototype GFP, from the jellyfish Aequorea victoria, is also unique in exhibiting highly efficient (>80%) proton transfer following absorption of a photon. Proton transfer contributes to most biological reactions, but typically takes place on time scales that are difficult to observe directly. The ability to trigger proton transfer with a femtosecond light pulse thus yields unequalled opportunities for understanding how proteins control this ubiquitous process. Our proposed investigations proposal is hypothesis-driven and aims to understand the dynamics and control of the ultrafast excited state proton transfer (ESPT) reaction. In particular, we hope to identify low frequency promoting vibrations that form an essential element of theoretical treatments of proton transfer. We present preliminary measurements of low frequency vibrational coherences that occur within the duration of the ESPT reaction. Control of ESPT in GFP is currently fervidly discussed and we propose to help resolve outstanding issues such as the enthalpic and entropic reaction barriers, the role of chromophore cooling, low frequency mode identification and assignment, and heterogeneity and interconversions of the protein-chromophore structure. Ultrafast kinetics, vibrational coherence spectroscopy (VCS), transient visible-visible and visible-infrared absorption spectroscopy, femtosecond stimulated Raman spectroscopy (FSRS), and coherent control spectroscopy will be used to dissect the microscopic details. Particular emphasis will be placed on temperature dependent studies. Further development of high level computational chemistry calculations that include the protein environment will aid in interpretation of the spectroscopic results. In turn, the experimental results will provide an essential calibration for the computational methods.