Development of Interface Specific Laser Temperature Jump Spectroscopy

2018 Fiscal Year Final Research Report

• Project/Area Number: 17K19096
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Research Field: Physical chemistry, Functional solid state chemistry, and related fields
• Research Institution: University of Tsukuba
• Principal Investigator: Masanari Okuno 筑波大学, 数理物質系, 助教 (00719065)
• Project Period (FY): 2017-06-30 – 2019-03-31
• Keywords: 界面・表面 / キラリティー / 二次構造 / タンパク質 / 偏光

Outline of Final Research Achievements

Secondary structures of proteins at proteins were investigated by hetero-dyne detected chiral vibrational sum frequency generation spectroscopy. Chiral VSFG spectroscopy detects not only chirality of bulk but also that of interfaces.
In this study, it was found that polarization dependence of chiral VSFG signals can be used for distinguishing the origin of chiral VSFG signals. Poly-lactic thin films, whose thicknesses were estimated to be several nm and several hundreds nm, were measured as a model of interfaces. Experimentally, it was shown that the PSP (P-polarized VSFG, S-polarized S visible, and P-polarized infrared) signal is similar to the SPP signal in that of the sign and amplitude in the reflection geometry as the simulation suggested. Relationships between molecular orientations of secondary structures and the signs of chiral VSFG signals were also partially elucidated in this study.

Free Research Field

分子分光学

Academic Significance and Societal Importance of the Research Achievements

本研究では、界面選択的な分光法を用いることで、タンパク質などの界面での性質を明らかにすることを目指した。タンパク質はαヘリックスやβシートなど、キラリティー（鏡像）を持つ。これまでに、界面選択的かつキラリティーを検出できる手法は存在しなかった。近年開発されたキラル振動和周波発生分光法は、界面のキラリティーを高感度に検出可能である。本研究では、キラル振動和周波発生の信号発生について、バルク相に由来するのか、界面に由来するのかを容易に決定できる手法を提案した。また、界面での二次構造の分子配向と、キラル振動和周波発生信号の符号の相関を研究した。