Spectroscopic Study on Protein Functionally-Relevant Modes Excited by Dynamics of Hydration Water

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K03559
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13040:Biophysics, chemical physics and soft matter physics-related
• Research Institution: Jichi Medical University
• Principal Investigator: Yamamoto Naoki 自治医科大学, 医学部, 助教 (90580671)
• Co-Investigator(Kenkyū-buntansha): 富永 圭介 神戸大学, 分子フォトサイエンス研究センター, 教授 (30202203) ; 中西 真大 福岡工業大学, 工学部, 助教 (00707763)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: タンパク質水和 / 広帯域誘電分光 / 中性子散乱 / ダイナミクスと機能の相関

Outline of Final Research Achievements

We attempted to quantify the complex dielectric spectra of hydrated protein in the sub-THz region (1 THz = 1012 Hz) in temperature and hydration-dependent manner. We were able to obtain the spectra at the region of 0.02-0.3 THz using a vector network analyzer (up to 50 GHz) and a THz time-domain spectrometer (0.5-0.3 THz), which we did not complete in the previous studies. By analyzing broadband dielectric spectra ranging from GHz to THz, it was suggested that there are spectral components possessing both rotational and vibrational properties in the sub-THz region, which we assume protein and hydration dynamics required for the protein functional expression. We also performed neutron scattering experiment on hydrated proteins, resulting in obtaining evidence of apparent contribution of unfreezable hydration water on the protein surface to protein dynamics.

Free Research Field

生物物理

Academic Significance and Societal Importance of the Research Achievements

本研究は、タンパク質まわりに存在する水、水和水がタンパク質ダイナミクスに果たす役割を理解するためのものであり、今回の結果より水和水とタンパク質の動きが互いに影響を及ぼしあうことでタンパク質の機能発現に必要な動きを活性化することが示唆された。また同時にその活性化が複雑な分子論的メカニズムによってもたらされることもわかり、計算機を用いた分子動力学シミュレーション等により理論的な理解を進める必要性があることもわかった。