This Article Free via Open Access: OA OA Full Text Full Text (PDF) Supplement OA All Versions of this Article: biophysj.107.118042v1 94/11/4435    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Google Scholar Articles by Joti, Y. Articles by Kitao, A. PubMed PubMed Citation Articles by Joti, Y. Articles by Kitao, A.

Hydration Effect on Low-Frequency Protein Dynamics Observed in Simulated Neutron Scattering Spectra

Yasumasa Joti ^* , Hiroshi Nakagawa , Mikio Kataoka   and Akio Kitao ^* 

^* Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan; Japan Science and Technology Agency, Core Research for Evolution Science and Technology, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan; Neutron Biophysics Group, Neutron Biology Research Center, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan; and Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan

Correspondence: Address reprint requests to Akio Kitao, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan. Tel.: 81-3-5841-2297; Fax: 81-3-5841-2297; E-mail: kitao{at}iam.u-tokyo.ac.jp.

Hydration effects on protein dynamics were investigated by comparing the frequency dependence of the calculated neutron scattering spectra between full and minimal hydration states at temperatures between 100 and 300 K. The protein boson peak is observed in the frequency range 1–4 meV at 100 K in both states. The peak frequency in the minimal hydration state shifts to lower than that in the full hydration state. Protein motions with a frequency higher than 4 meV were shown to undergo almost harmonic motion in both states at all temperatures simulated, whereas those with a frequency lower than 1 meV dominate the total fluctuations above 220 K and contribute to the origin of the glass-like transition. At 300 K, the boson peak becomes buried in the quasielastic contributions in the full hydration state but is still observed in the minimal hydration state. The boson peak is observed when protein dynamics are trapped within a local minimum of its energy surface. Protein motions, which contribute to the boson peak, are distributed throughout the whole protein. The fine structure of the dynamics structure factor is expected to be detected by the experiment if a high resolution instrument (<20 µeV) is developed in the near future.

This article has been cited by other articles:

				H. Nakagawa, Y. Joti, A. Kitao, and M. Kataoka Hydration Affects Both Harmonic and Anharmonic Nature of Protein Dynamics Biophys. J., September 15, 2008; 95(6): 2916 - 2923. [Abstract] [Full Text] [PDF]