Method to measure vibrational spectra of proteins in aqueous solution for detection of intermolecular interactions using solid/liquid interface

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05415
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 32010:Fundamental physical chemistry-related
• Research Institution: University of Tsukuba
• Principal Investigator: Masato Kondoh 筑波大学, 数理物質系, 助教 (20611221)
• Co-Investigator(Kenkyū-buntansha): 石橋 孝章 筑波大学, 数理物質系, 教授 (70232337)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 生体分子 / 振動スペクトル / 固液界面 / 振動和周波発生分光 / 全内部反射ラマン分光 / 脂質膜

Outline of Final Research Achievements

In this study, I have applied interface-sensitive spectroscopy to proteins immobilized at a solid/aqueous solution interface to develop a new method to obtain vibrational spectra of biomolecules in aqueous environment with high-sensitivity. For this purpose, I have developed and improved a CaF2 substrate coated by a thin layer of silica. I was initially going to fix protein samples chemically on the silica-coated surface of this substrate using silane coupling agents. However, in the middle of the research, some problems arose concerning the flatness of the coated surface of the substrate, and they made it difficult to move the project.
Thus, I reconsidered the project and performed experiments to measure vibrational spectra of alamethicin, one of membrane-binding peptides, interacting with lipid bilayer membranes prepared at a solid/aqueous solution interface. As a result, I have successfully detected Raman bands of alamethicin interacting with phospholipid bilayers.

Free Research Field

分子分光学

Academic Significance and Societal Importance of the Research Achievements

界面敏感なラマン分光法で，界面にある脂質膜と相互作用した膜結合ペプチドの振動スペクトルを検出できたことが本研究の主な成果である．概要の項目で述べたように，途中に計画を見直したが，当初着目した「界面を利用する」という独自の視点で取り組んだ研究である．膜結合ペプチドは，抗生物質としての重要な働きを持つ．その抗菌作用は，ペプチドが細胞膜と結合し，膜に侵入して孔をあけることで発現する．抗菌作用の機構を理解するには，膜とペプチドの相互作用を調べることが不可欠である．本研究の学術的意義は，こうした相互作用を，界面を利用した新しい視点から研究する方法を与えたことにある．