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Terahertz collective dynamics of biopolymers in water: THz absorption and circular dichroism spectroscopy.

机译：太赫兹生物聚合物在水中的集体动力学：太赫兹吸收和圆二色谱。

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摘要

Biopolymers are expected to exhibit broad spectral features in the terahertz frequency range, corresponding to their functionally relevant, global and sub-global collective vibrational modes with approximately picosecond timescales. Recent advances in terahertz source and detection methods have stimulated experimental researchers to employ terahertz absorption spectroscopy to directly probe and confirm these postulated collective vibrational modes. However, these pioneering studies have been limited to dry and, at best, moist samples. Successful isolation of the low frequency vibrational activities of solvated biomolecules in their natural water environment has remained elusive, due to the overwhelming attenuation of the terahertz radiation by water.;In an effort to probe the terahertz dynamics in solvated biopolymers, I have adopted two distinct and complementary techniques: terahertz absorption spectroscopy and terahertz circular dichroism (TCD) spectroscopy. I have developed a terahertz absorption and circular dichroism spectrometer suitable for studying biomolecules in biologically relevant water solutions. The spectrometer combines intense terahertz radiation (UCSB Free-Electron Lasers, harmonic multipliers, and a Gunn oscillator, with an ultra sensitive cryogenic detector, a precision variable path length sample cell, and a polarizing interferometer.;I have isolated, for the first time, the terahertz absorption of solvated prototypical proteins, and have made important direct comparison to the existing theoretical calculations. Using our TCD spectrometer, with current resolution reaching below one part in one thousand, we have successfully demonstrated the magnetic circular dichroism in semiconductors, and placed upper bounds on the TCD signatures of prototypical proteins in aqueous solution. Work remains to achieve the requisite instrumental sensitivity to recover TCD signatures of biological materials in solution phase.
机译：预计生物聚合物将在太赫兹频率范围内展现出广泛的光谱特征，这与它们的功能相关，整体和亚整体的集体振动模式（大约为皮秒级）相对应。太赫兹源和检测方法的最新进展刺激了实验研究人员采用太赫兹吸收光谱法直接探测和确认这些假定的集体振动模式。但是，这些开创性研究仅限于干燥和最好是潮湿的样品。由于水对太赫兹辐射的压倒性衰减，在自然水环境中成功分离溶剂化生物分子的低频振动活动仍然难以捉摸。以及互补技术：太赫兹吸收光谱和太赫兹圆二色性（TCD）光谱。我已经开发了太赫兹吸收和圆二色光谱仪，适用于研究与生物有关的水溶液中的生物分子。该光谱仪结合了太赫兹辐射（UCSB自由电子激光器，谐波倍增器和Gunn振荡器），以及超灵敏的低温检测器，精密可变路径长度的样品池和偏振干涉仪。 ，是溶剂化原型蛋白质的太赫兹吸收，并且与现有的理论计算作了重要的直接比较；使用我们的TCD光谱仪，电流分辨率达到千分之一以下，我们已经成功地证明了半导体中的磁性圆二色性水溶液中原型蛋白的TCD标记的上限，仍需要努力以达到必要的仪器灵敏度，以恢复溶液相中生物材料的TCD标记。

著录项

  • 作者

    Xu, Jing.;

  • 作者单位

    University of California, Santa Barbara.;

  • 授予单位 University of California, Santa Barbara.;
  • 学科 Biophysics General.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 86 p.
  • 总页数 86
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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