Exploiting Chromophore-Protein Interactions through Linker Engineering To Tune Photoinduced Dynamics in a Biomimetic Light-Harvesting Platform
Exploiting Chromophore-Protein Interactions through Linker Engineering To Tune Photoinduced Dynamics in a Biomimetic Light-Harvesting Platform
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DOI：
10.1021/jacs.7b13598
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发表时间：
2018-05-23
影响因子：
15
通讯作者：
Ginsberg, Naomi S.
中科院分区：
文献类型：
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作者：
Delor, Milan;Dai, Jing;Ginsberg, Naomi S.
创造模仿并超越自然界中发现的人工系统是现代科学的重大挑战之一。在光合作用光收集的背景下，困难在于最大限度地控制密集排列阵列中发色团的能量、位置和相对取向，以高效地将电子激发能量转移到所需的位置。为了实现这一目标，我们使用了一种高度通用的仿生蛋白支架，该支架来自烟草花叶病毒外壳蛋白，它可以通过不同长度和刚性的连接物将发色团附着在精确的位置。我们发现，轻微的连接基修饰，包括改变手性构型和烷基缩短，会导致系统的超快激发态动力学显著延长，因为连接基被缩短和刚性。分子动力学模拟提供了分子水平的细节，说明生色团的附着方向、位置和与蛋白质表面的距离如何导致系统动力学中观察到的趋势。特别是，我们发现短而刚性的连接物能够将水分子夹在生色团和蛋白质之间，导致生色团-水-蛋白质超复合体具有错综复杂的耦合动力学，这高度依赖于它们所在的局部蛋白质环境。此外，基于环己基的连接体被认为是在几纳秒内保持旋转关联并从而在激子寿命中锁定相对发色团取向的理想候选者。将连接子工程与在水合蛋白支架上明智地放置发色团相结合，以利用不同的发色团-浴耦合，提供了一条清晰而有效的途径，以产生高度可控的人工捕光系统，从而能够越来越多地模拟它们的自然对应物，从而有助于阐明自然的光合作用机制。
Creating artificial systems that mimic and surpass those found in nature is one of the great challenges of modern science. In the context of photosynthetic light harvesting, the difficulty lies in attaining utmost control over the energetics, positions and relative orientations of chromophores in densely packed arrays to transfer electronic excitation energy to desired locations with high efficiency. Toward achieving this goal, we use a highly versatile biomimetic protein scaffold from the tobacco mosaic virus coat protein on which chromophores can be attached at precise locations via linkers of differing lengths and rigidities. We show that minor linker modifications, including switching chiral configurations and alkyl chain shortening, lead to significant lengthening of the ultrafast excited state dynamics of the system as the linkers are shortened and rigidified. Molecular dynamics simulations provide molecular-level detail over how the chromophore attachment orientations, positions, and distances from the protein surface lead to the observed trends in system dynamics. In particular, we find that short and rigid linkers are able to sandwich water molecules between chromophore and protein, leading to chromophore-water-protein supracomplexes with intricately coupled dynamics that are highly dependent on their local protein environment. In addition, cyclohexyl-based linkers are identified as ideal candidates to retain rotational correlations over several nanoseconds and thus lock relative chromophore orientations throughout the lifetime of an exciton. Combining linker engineering with judicious placement of chromophores on the hydrated protein scaffold to exploit different chromophore-bath couplings provides a clear and effective path to producing highly controllable artificial light-harvesting systems that can increasingly mimic their natural counterparts, thus aiding to elucidate natural photosynthetic mechanisms.