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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Energy transport in peptide helices
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Energy transport in peptide helices

机译：肽螺旋中的能量传输

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摘要

We investigate energy transport through an α-aminoisobutyric acid-based 3_(10)-helix dissolved in chloroform in a combined experimental-theoretical approach. Vibrational energy is locally deposited at the N terminus of the helix by ultrafast internal conversion of a covalently attached, electronically excited, azobenzene moiety. Heat flow through the helix is detected with subpicosecond time resolution by employing vibrational probes as local thermometers at various distances from the heat source. The experiment is supplemented by detailed nonequilibrium molecular dynamics (MD) simulations of the process, revealing good qualitative agreement with experiment: Both theory and experiment exhibit an almost instantaneous temperature jump of the reporter units next to the heater which is attributed to the direct impact of the isomerizing azobenzene moiety. After this impact event, helix and azobenzene moiety appear to be thermally decoupled. The energy deposited in the helix thermalizes on a subpicosecond timescale and propagates along the helix in a diffusive-like process, accompanied by a significant loss into the solvent. However, in terms of quantitative numbers, theory and experiment differ. In particular, the MD simulation seems to overestimate the heat diffusion constant (2 A~2 ps~(-1) from the experiment) by a factor of five.
机译：我们通过组合的实验理论方法研究了通过溶解在氯仿中的基于α-氨基异丁酸的3_（10）-螺旋的能量传输。通过共价连接的电子激发的偶氮苯部分的超快内部转化，振动能局部沉积在螺旋的N末端。通过使用振动探针作为局部温度计，在距热源不同距离处，以亚皮秒时间分辨率检测通过螺旋的热流。实验还辅以详细的过程非平衡分子动力学（MD）模拟，揭示了与实验的良好定性一致性：理论和实验均显示了加热器附近报告单元的几乎瞬时温度跃迁，这归因于加热器的直接影响。异构化的偶氮苯部分。在此冲击事件之后，螺旋和偶氮苯部分似乎发生了热解耦。沉积在螺旋中的能量在亚皮秒级的时间范围内发生热化，并以类似于扩散的过程沿螺旋传播，并伴有大量损失到溶剂中。但是，在数量上，理论和实验有所不同。特别是，MD模拟似乎高估了热扩散常数（实验得出的2 A〜2 ps〜（-1））。

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