The orientation of a membrane probe from structural analysis by enhanced Raman scattering
The orientation of a membrane probe from structural analysis by enhanced Raman scattering
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DOI：
10.1016/j.bbamem.2019.183109
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发表时间：
2020-02-01
影响因子：
3.4
通讯作者：
Hafner, Jason H.
中科院分区：
文献类型：
--
作者：
Hughes, Hannah J.;Demers, Steven M. E.;Hafner, Jason H.
荧光小分子被广泛用作生物膜的探针。不同的探针光学指示膜的性质，如脂质相，厚度，粘度和电位。探针信号背后的详细分子机制尚未得到很好的理解，部分原因是缺乏工具来确定探针在膜中的位置和方向。光学测量对齐的生物膜和脂质双层提供一定程度的取向信息的基础上各向异性的吸收，荧光，或非线性光学特性。这些方法通常发现膜法线和分子长轴之间的极性倾斜角。在这里，我们表明，金纳米棒上的脂质膜的溶液相表面增强拉曼散射（Sers）光谱可用于确定膜内分子的分子取向。研究了电压敏感染料4-（2-（6-（二丁氨基）-2-萘基）-1-（3-磺丙基）-氢氧化物（简称二-4-ANEPPS）。通过对Sers谱中几个峰的分析，发现分子的极角与膜法线的夹角为66度，分子绕长轴的滚动角与原来的取向夹角为305度。这种结构分析方法可以帮助阐明荧光膜探针信号的含义，以及它们如何受到不同脂质成分的影响。
Small fluorescent molecules are widely used as probes of biomembranes. Different probes optically indicate membrane properties such as the lipid phase, thickness, viscosity, and electrical potential. The detailed molecular mechanisms behind probe signals are not well understood, in part due to the lack of tools to determine probe position and orientation in the membrane. Optical measurements on aligned biomembranes and lipid bilayers provide some degree of orientational information based on anisotropy in absorption, fluorescence, or nonlinear optical properties. These methods typically find the polar tilt angle between the membrane normal and the long axis of the molecule. Here we show that solution-phase surface enhanced Raman scattering (SERS) spectra of lipid membranes on gold nanorods can be used to determine molecular orientation of molecules within the membrane. The voltage sensitive dye 4-(2-(6-(dibutylamino)-2-naphthalenypetheny1)-1-(3-sulfopropyl)-hydroxide, known as di-4-ANEPPS, is studied. Through the analysis of several peaks in the SERS spectrum, the polar angle from the membrane normal is found to be 66 degrees, and the roll angle around the long axis of the molecule to be 305 degrees from the original orientation. This structural analysis method could help elucidate the meaning of fluorescent membrane probe signals, and how they are affected by different lipid compositions.