Terahertz spectral of enantiomers and racemic amino acids by time-domain-spectroscopy technology

• Published in: Infrared physics & technology 2019-01, Vol.96, p.17-21
• Main Authors: Liu, Yan, Zhou, Tao, Cao, Jun-Cheng
• Format: Article
• Language: English
• Subjects: Amino acids; Collective vibration; Density functional theory; Isomers; Terahertz time-domain spectroscopy
• ISSN: 1350-4495; 1879-0275
• DOI: 10.1016/j.infrared.2018.10.026

•The absorption spectra of valine were mainly studied.•It is proved that terahertz time-domain spectroscopy can be well used for the identification of biological macromolecules.•At the same time, the absorption spectra of histidine, leucine and methionine are studied, which makes the results more convincing.•The spectrum of valine is simulated by using Materials studio software. The number of peaks is consistent with the experimental results, which further proves the accuracy of the results. The absorption spectra of four amino acids were studied. These spectra are obtained by terahertz time-domain spectroscopy (TDS) technique. The four amino acids are alanine, methionine, leucine, and valine, respectively. The spectra of their enantiomers (l-, d-) and racemic compounds (dl-) were investigated. Although the two isomers have very similar structures, their absorption spectra are obviously different. The absorption coefficient of each structure is calculated by the density functional theory (DFT), and the simulated spectra of each structure are obtained. It is shown that the number of the calculated peaks is in good agreement with the experimental ones. The experimental spectra were compared with the theoretical spectra. The differences between the absorption spectra of isomers are presented, and the reasons for the differences were analyzed. The vibratory spectra of biomolecules were studied, and the correlation between molecular structure and function was further understood.