Development of total internal reflection transient grating system to monitor ion pump dynamics of rhodopsin in a lipid bilayer

2019 Fiscal Year Final Research Report

• Project/Area Number: 18K14175
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 32010:Fundamental physical chemistry-related
• Research Institution: University of Tsukuba
• Principal Investigator: Kondoh Masato 筑波大学, 数理物質系, 助教 (20611221)
• Project Period (FY): 2018-04-01 – 2020-03-31
• Keywords: 過渡回折格子法 / 分子拡散 / 脂質二重膜 / 固液界面

Outline of Final Research Achievements

A method based on the transient grating (TG) technique with total internal reflection geometry for probe light (TIR-TG) has been developed to detect conformational and ion transportation dynamics of rhodopsin proteins in a lipid bilayer membrane. In this study, we constructed a TIR-TG apparatus and applied it to diffusion coefficient measurements of stilbene in a dimyristoylphosphatidylcholine (DMPC) lipid bilayer membrane at a silica/water interface. As a result, we found that the stilbene molecules in the DMPC bilayer membrane show two different diffusion coefficients. This result indicates that the DMPC membrane is an inhomogeneous environment that can be described with two different effective viscosities.

Free Research Field

分子分光学

Academic Significance and Societal Importance of the Research Achievements

生体膜は，光合成や物質輸送などの生化学過程の場である．膜の構造や膜中での分子の動きを観測し，明らかにすることは，現代の分子科学の重要な課題の一つである．本研究では，固体と溶液の界面に保持した脂質二重膜の系に，界面敏感な過渡回折格子法を適用するという着想に基づき，膜中での分子拡散測定を行った．この測定を通して，膜の不均一構造を実験的に支持する意義深い結果を得た．また，膜タンパク質の構造や動きを生理環境に近い膜中で観測するための方法論の基礎を構築できた．このことが，学術的に意義深い．