Energy transport in peptide helices
Energy transport in peptide helices
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DOI：
10.1073/pnas.0701762104
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发表时间：
2007-07-31
影响因子：
11.1
通讯作者：
Hamm, Peter
中科院分区：
文献类型：
--
作者：
Botan, Virgiliu;Backus, Ellen H. G.;Hamm, Peter
我们研究了通过a-氨基异丁酸为基础的3（10）-螺旋溶解在氯仿中的能量传输的实验和理论相结合的方法。振动能量局部沉积在N末端的螺旋通过超快内部转换的共价连接，电子激发，偶氮苯部分。通过螺旋的热流检测与亚皮秒的时间分辨率采用振动探头作为本地温度计在不同的距离从热源。该实验是由详细的非平衡态分子动力学（MD）模拟的过程中，揭示了良好的定性与实验一致：理论和实验表现出几乎瞬时的温度跳变的记者单位旁边的加热器，这是由于异构化偶氮苯部分的直接影响。在这种影响事件之后，螺旋和偶氮苯部分似乎是热解耦的。沉积在螺旋中的能量在亚皮秒时间尺度上热化，并在扩散样过程中沿着螺旋传播，伴随着大量损失到溶剂中。然而，就数量而言，理论和实验不同。特别是，MD模拟似乎高估了热扩散常数（实验中为2埃（2）ps（-1）），高估了5倍。
We investigate energy transport through an a-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 angstrom(2) ps(-1) from the experiment) by a factor of five.