Low-frequency dynamics of biological molecules studied by terahertz time-domain spectroscopy

Issue title: From Molecule to Tissue: XIII European Conference on the Spectroscopy of Biological Molecules, Palermo, Italy, August 28–September 2, 2009, Part 1 of 2

Article type: Research Article

Authors: Kawaguchi, Shintaro | Kambara, Ohki | Ponseca Jr., Carlito S. | Shibata, Mikihiro | Kandori, Hideki | Tominaga, Keisuke^{; ;}

Affiliations: Graduate School of Science, Kobe University, Nada, Kobe, Japan | Molecular Photoscience Research Center, Kobe University, Nada, Kobe, Japan | Nagoya Institute of Technology, Showa-ku, Nagoya, Japan

Note: [] Corresponding author: Dr. Keisuke Tominaga, Graduate School of Science, Kobe University, Nada, Kobe, 657-8501, Japan. E-mail: [email protected].

Abstract: By terahertz (THz) time-domain spectroscopy we have measured low-frequency spectra of amino acid (glycine; Gly), short peptides ((Gly)3 and (Gly)4), six globular proteins and bacteriorhodopsin (BR). From the analysis of the THz spectra we defined and obtained the reduced absorption cross sections for these cases, which are proportional to the vibrational density of states. We observed anharmonic behaviors in the low-frequency modes of the short peptides. The globular proteins we investigated show a universal feature in the low-frequency spectra. BR shows the dynamical transition in the temperature dependence of the THz spectrum when the sample is hydrated.

Keywords: Terahertz time-domain spectroscopy, globular protein, bacteriorhodopsin

DOI: 10.3233/SPE-2010-0423

Journal: Spectroscopy, vol. 24, no. 1-2, pp. 153-158, 2010