Observation of coherent delocalized phonon-like modes in DNA under physiological conditions.
Observation of coherent delocalized phonon-like modes in DNA under physiological conditions.
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DOI：
10.1038/ncomms11799
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发表时间：
2016-06-01
影响因子：
16.6
通讯作者：
Wynne K
中科院分区：
文献类型：
--
作者：
González-Jiménez M;Ramakrishnan G;Harwood T;Lapthorn AJ;Kelly SM;Ellis EM;Wynne K
欠阻尼太赫兹频率离域类声子模式长期以来一直被认为在DNA的生物功能中发挥作用。这种声子模式涉及许多原子的集体运动，是理解宏观构象变化和相关生物化学现象的分子本质的先决条件。最初的预测是基于DNA的简单理论模型。然而，这种模型没有考虑到与周围水的强烈相互作用，这可能导致声子模式被严重阻尼和局部化。在这里，我们应用最先进的飞秒光学克尔效应光谱，这是目前唯一的技术能够采取低频（GHz至太赫兹）振动光谱的解决方案。我们能够证明，声子模式涉及链之间的氢键网络存在于DNA中的生理相关条件。此外，与本体相比，溶剂化水分子的动力学减慢约20倍。 太赫兹频率振动模式被认为对DNA生物功能起着关键作用，但迄今为止，在溶液中观察这些波动已被证明是困难的。在这里，作者使用飞秒光学克尔效应光谱来证明它们在生理相关条件下的存在。
Underdamped terahertz-frequency delocalized phonon-like modes have long been suggested to play a role in the biological function of DNA. Such phonon modes involve the collective motion of many atoms and are prerequisite to understanding the molecular nature of macroscopic conformational changes and related biochemical phenomena. Initial predictions were based on simple theoretical models of DNA. However, such models do not take into account strong interactions with the surrounding water, which is likely to cause phonon modes to be heavily damped and localized. Here we apply state-of-the-art femtosecond optical Kerr effect spectroscopy, which is currently the only technique capable of taking low-frequency (GHz to THz) vibrational spectra in solution. We are able to demonstrate that phonon modes involving the hydrogen bond network between the strands exist in DNA at physiologically relevant conditions. In addition, the dynamics of the solvating water molecules is slowed down by about a factor of 20 compared with the bulk. Terahertz-frequency vibrational modes are thought to play a key role for DNA biological functions, yet observation of these fluctuations in solution has proven difficult so far. Here, the authors use femtosecond optical Kerr-effect spectroscopy to demonstrate their existence in physiologically relevant conditions.