太赫兹是指频率从0.1到2.0THz之间的远红外波。与傅里叶红外相比,太赫兹时域光谱能量低,信躁比高,并且无辐射损伤。氨基酸分子的低频振动模式(扭转,集体振动模式和氢键)处在THz波段。氨基酸是一类重要的生物分子,是组成蛋白质最基本的物质。氨基酸分子以分子间氢键相互连接构成晶体。氨基酸在THz波段比在红外波段体现更多独特吸收特征。到目前为止,已经获得了20种氨基酸分子的太赫兹吸收谱,包括利用太赫兹技术对部分氨基酸的定量分析。氨基酸的太赫兹光谱研究,有利于深层次理解蛋白质/DNA的低频振动模式及相关生物反应和活性。文章综述了20种氨基酸分子的太赫兹吸收光谱并建立了吸收光谱数据库。总结了太赫兹技术在氨基酸应用方面存在的问题,并对未来发展方向进行展望。
Terahertz (THz) is the frequency region ranging from 0.1 to 2.0 THz, which lies in the far-infrared region. Compared to Fourier transform infrared spectra (FTIR), terahertz time-domain spectra (THz-TDS) has low energy, high signal-tonoise ratio (SNR) and is non-ionizing radiation. Low-frequency vibrational modes of some amino acids, such as torsional and collective vibrational modes and hydrogen-bond modes, exist in the THz region. Amino acids are important organic compounds and are the fundamental components of proteins. Amino acids can exist with a highly ordered crystal structure linked by hydrogen intermolecular bonds in the solid phase. The absorption spectra of amino acids in the THz region show marked differences while mid-infrared absorption spectra usually show very little difference. Up to now, absorption spectra of twenty kinds of amino acids have been studied by many researchers using THz technique; the quantitative analysis of amino acids by THZ-TDS is also included. Investigation of THz spectra of amino acids are of fundamental interests, and will lead to further understanding of low-frequency vibrations of protein/DNA and relevant biological reactions and activities. In the present paper, the latest progress in absorption spectra of amino acids determined by THz spectroscopy is reviewed and a database is built. Some brief remarks on future developments in and prospects for THz application in amino acids are also provided.