Development of electron nano-diffraction for the study on membrane structures

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K15107
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Biophysics
• Research Institution: Kyushu University
• Principal Investigator: Kinoshita Masanao 九州大学, 理学研究院, 助教 (40529517)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 電子線散乱 / 脂質膜 / 炭素鎖充填構造 / 相分離

Outline of Final Research Achievements

Ordered/disordered phase separation occurring in bio-membranes has attracted researchers' interests since the ordered domains, lipid rafts, are involved in important biological events. While the structure of the ordered domain has been examined with artificial membranes, the substructure inside the ordered domain is not unknown. Here, we examined the packing structure of the lipid carbon chains in the ordered domain using electron diffraction.
We first prepared the dehydrated monolayer samples, which maintain the chain packing structures as those in the aqueous suspension. We then optimized the electron flux to minimize beam damage and developed low-flux scanning electron diffraction (LFSED). Finally, we addressed the chain packing structure inside the ordered domain and found that the ordered domain contains multiple subdomains with different crystallographic axes. Moreover, the size of the subdomain is larger in the domain centre than that near the phase boundary.

Free Research Field

生物物理

Academic Significance and Societal Importance of the Research Achievements

本研究で開発した低流量走査電子線散乱(LFSED)法により、1)直径1μmの領域の構造情報を選択的かつ非侵襲的に取得することができるようになった。また、2)X線より散乱能に優れた電子線を用いることで、脂質単分子膜からでも十分な強度の散乱を取得できた。3)高輝度放射光施設を必要とするX線散乱に比べ、LFSEDは通常の電子顕微鏡で行うことができる。さらに電子線散乱は脂質膜のみならずタンパク質など様々な生体材料の構造解析に適応できることを勘案すると、本手法は生命科学分野の発展に大きく貢献できる。