Direct Measurement of the Membrane Dipole Field in Bicelles Using Vibrational Stark Effect Spectroscopy
Direct Measurement of the Membrane Dipole Field in Bicelles Using Vibrational Stark Effect Spectroscopy
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DOI：
10.1021/jz200729a
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发表时间：
2011-08-04
影响因子：
5.7
通讯作者：
Webb, Lauren J.
中科院分区：
文献类型：
--
作者：
Hu, Wenhui;Webb, Lauren J.
脂质双层膜中的静电场影响膜相关蛋白的结构和功能。我们在这里提出的第一个直接测量的膜偶极静电场在脂bicelles使用振动斯塔克效应光谱，其中腈振荡器的振动频率的变化，以响应其本地的静电环境。我们合成了α-螺旋肽，其在螺旋上的沿着四个位置含有非天然氨基酸对氰基苯丙氨酸（CN-Phe）。将该肽插入由1，2-二肉豆蔻酰-sn-甘油-3-磷酸胆碱（DMPC）和1，2-二己酰-sn-甘油-3-磷酸胆碱（DHPC）组成的半径为5和15 nm的双胞中。腈探针在沿螺旋轴沿着的每个位置处的振动吸收能量的变化用于确定探针的局部静电场的变化。我们测得的膜偶极静电场的大小为-6 MV/cm，在膜表面附近变化迅速，在低介电膜内部变化较慢。
Electrostatic fields in lipid bilayer membranes influence the structure and function of membrane-associated proteins. We present here the first direct measurement of the membrane dipole electrostatic field in lipid bicelles using vibrational Stark effect spectroscopy, in which a nitrile oscillator's vibrational frequency changes in response to its local electrostatic environment. We synthesized a-helical peptides containing the unnatural amino acid p-cyanophenylalanine (CN-Phe) at four locations along the helix. This peptide was intercalated into bicelles 5 and 15 nm in radius composed of mixtures of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC). Changes in the vibrational absorption energy of the nitrile probe at each position along the helical axis were used to determine changes in the local electrostatic field of the probe. We measured the magnitude of the membrane dipole electrostatic field to be -6 MV/cm, changing rapidly near the membrane surface and more slowly in the low dielectric membrane interior.