Terahertz Time-Domain and Raman Studies of Sulfur-Containing Polypeptides

We present the THz and Raman spectra of sulfur-containing di-and tetrapeptides in the form of molecular polycrystalline powder and in solution. The spectra measured in far-infrared region with the use of terahertz (THz) time-domain spectroscopic technique. The spectral features in THz and Raman spectra are different among sulfur-containing di-and tetrapeptides. We are discussing the possibility to observe and to assign the low-frequency THz and Raman lines to the disulfide bridges. The experimental results are compared with ab initio calculations to discuss assignment of the vibrational modes. In addition the possibility to observe the low frequency the molecular motions in native liquids and the mixtures is discussed.