Ultrabroadband terahertz spectroscopies of biomolecules and water
Ultrabroadband terahertz spectroscopies of biomolecules and water
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DOI：
10.1117/12.2003796
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发表时间：
2013-03
期刊：
影响因子：
--
通讯作者：
D. Turton;Thomas Harwood;A. Lapthorn;E. Ellis;K. Wynne
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文献类型：
--
作者：
D. Turton;Thomas Harwood;A. Lapthorn;E. Ellis;K. Wynne
我们描述了一系列现代光谱技术的使用--从太赫兹时域光谱（THz- TDS）到高动态范围的飞秒光学克尔效应（OKE）光谱--来研究蛋白质、肽和其他生物分子与水的相互作用。溶剂。蛋白质中的化学反应需要快速的皮秒波动来达到过渡态，以耗散能量，并且（可能）减少沿反应坐标沿着的能垒的宽度和高度。这种运动与水溶剂的结构和动力学有关，使得水合作用对功能至关重要。这些动力学发生在一个巨大的时间尺度范围内：从蛋白质的第一溶剂化壳层中的水分子扩散的纳秒时间尺度，氨基酸侧链的皮秒运动，以及水的亚皮秒振动和声子样运动。它示出，从MHz到太赫兹的大范围的频率是可直接使用OKE，从而减少各向异性拉曼光谱，并通过使用包括太赫兹-TDS的技术的组合，从而在介电谱。使用这些技术，我们现在可以在3-30 THz范围内观察到水溶剂中蛋白质光谱的显著差异，并在较低频率（10 GHz-3 THz）下观察到更细微的差异。
We describe the use of a range of modern spectroscopic techniques—from terahertz time-domain spectroscopy (THz- TDS) to high dynamic-range femtosecond optical Kerr-effect (OKE) spectroscopy—to study the interaction of proteins, peptides, and other biomolecules with the aqueous solvent. Chemical reactivity in proteins requires fast picosecond fluctuations to reach the transition state, to dissipate energy, and (possibly) to reduce the width and height of energy barriers along the reaction coordinate. Such motions are linked with the structure and dynamics of the aqueous solvent making hydration critical to function. These dynamics take place over a huge range of timescales: from the nanosecond timescale of diffusion of water molecules in the first solvation shell of proteins, picosecond motions of amino-acid side chains, and sub-picosecond librational and phonon-like motions of water. It is shown that a large range of frequencies from MHz to THz is accessible directly using OKE resulting in the reduced anisotropic Raman spectrum and by using a combination of techniques including THz-TDS resulting in the dielectric spectrum. Using these techniques, we can now observe very significant differences in the spectra of proteins in aqueous solvent in the 3-30 THz range and more subtle differences at lower frequencies (10 GHz-3 THz).