Low-frequency dynamics of proteins studied by terahertz time-domain spectroscopy

PHYS 359

Keisuke Tominaga, tominaga@kobe-u.ac.jp1, Shintaro Kawaguchi2, Ohki Kambara1, Mikihiro Shibata3, and Hideki Kandori3. (1) Molecular Photoscience Research Center, Kobe University, Rokkodai 1-1, Nada-Ku, Kobe, 657-8501, Japan, (2) Department of Chemistry, Graduate School of Science, Kobe University, Rokkodai 1-1, Nada-ku, Kobe, 657-8501, Japan, (3) Department of Materials and Engineering, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan
When proteins express their functions, large conformational changes often occur. These conformational changes result from collective motions of a large number of atoms. Such motions of proteins have characteristic frequencies in the low-frequency region below a few tens of wavenumbers. In this work we have measured the low-frequency spectra of various proteins such as bacteriorhodopsin (BR) and hen egg white lysozyme in the ground state using terahertz time-domain spectroscopy (THz-TDS) to investigate relation among the low-frequency motions, three-dimensional structures, and expression of their function. From the obtained THz spectra we calculated a physical quantity which is proportional to vibrational density of states (VDOS) in the low-frequency region. It was found that the VDOS of all the BR samples show power-law behavior, and the exponents are close to two. From the observation we discuss the low-frequency dynamics and anharmonic couplings among the low-frequency motions.
 

PHYS Poster Session - Multiscale Modeling in Biophysics
7:30 PM-10:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Hall A, Poster

Sci-Mix
8:00 PM-10:00 PM, Monday, April 7, 2008 Morial Convention Center -- Hall A, Sci-Mix

Division of Physical Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008