Long-lived quantum coherence in photosynthetic complexes at physiological temperature
Long-lived quantum coherence in photosynthetic complexes at physiological temperature
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DOI：
10.1073/pnas.1005484107
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发表时间：
2010-07-20
影响因子：
11.1
通讯作者：
Engel, Gregory S.
中科院分区：
文献类型：
--
作者：
Panitchayangkoon, Gitt;Hayes, Dugan;Engel, Gregory S.
光合天线复合体通过将激发转移到反应中心来捕获和集中太阳辐射，该反应中心以化学键的形式存储来自光子的能量。这个过程以近乎完美的量子效率发生。最近在低温下的实验已经揭示了相干能量传递--一种波动式的传递机制--发生在许多光合色素-蛋白质复合物中。使用Fenna-Matthews-Olson天线复合物（FMO）作为模型系统，结合非相干和相干转移以及热失相的理论研究预测，环境辅助的量子转移效率在生理温度附近达到峰值;这些研究还表明，这种机制同时提高了能量转移过程的鲁棒性。这个理论需要在室温下长寿命的量子相干性，这在FMO中从未观察到。在这里，我们提出的证据表明，量子相干生存在FMO在生理温度至少300 fs，足够长的时间来影响生物能量传输。这些数据证明，在77 K下发现的波浪状能量传递过程与生物功能直接相关。在显微镜下，我们将这种长的相干寿命归因于包裹发色团的蛋白质基质内的相关运动，并且我们发现蛋白质提供的保护程度在77 K和277 K之间似乎是恒定的。蛋白质塑造能量景观，并介导有效的能量转移，尽管热波动。
Photosynthetic antenna complexes capture and concentrate solar radiation by transferring the excitation to the reaction center that stores energy from the photon in chemical bonds. This process occurs with near-perfect quantum efficiency. Recent experiments at cryogenic temperatures have revealed that coherent energy transfer-a wave-like transfer mechanism-occurs in many photosynthetic pigment-protein complexes. Using the Fenna-Matthews-Olson antenna complex (FMO) as a model system, theoretical studies incorporating both incoherent and coherent transfer as well as thermal dephasing predict that environmentally assisted quantum transfer efficiency peaks near physiological temperature; these studies also show that this mechanism simultaneously improves the robustness of the energy transfer process. This theory requires long-lived quantum coherence at room temperature, which never has been observed in FMO. Here we present evidence that quantum coherence survives in FMO at physiological temperature for at least 300 fs, long enough to impact biological energy transport. These data prove that the wave-like energy transfer process discovered at 77 K is directly relevant to biological function. Microscopically, we attribute this long coherence lifetime to correlated motions within the protein matrix encapsulating the chromophores, and we find that the degree of protection afforded by the protein appears constant between 77 K and 277 K. The protein shapes the energy landscape and mediates an efficient energy transfer despite thermal fluctuations.