The preference of tryptophan for membrane interfaces
The preference of tryptophan for membrane interfaces
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DOI：
10.1021/bi980809c
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发表时间：
1998-10-20
期刊：
影响因子：
2.9
通讯作者：
White, SH
中科院分区：
文献类型：
--
作者：
Yau, WM;Wimley, WC;White, SH
膜蛋白的一个普遍特征是色氨酸和酪氨酸残基倾向于膜表面，这可能是由于独特的界面相互作用而增强了稳定性。这种倾向的物理基础被广泛认为源于与亚氨基氢键和/或偶极相互作用相关的两亲性相互作用。我们通过使用¹H魔角旋转（MAS）化学位移测量、二维（2D）核奥弗豪泽效应光谱（2D - NOESY）¹H MAS NMR以及固态²H NMR研究四种色氨酸类似物与磷脂酰胆碱膜的相互作用，检验了色氨酸界面倾向的这些及其他可能性。我们发现这些类似物位于甘油基团附近，它们都会引起酰基链组织类似的适度变化，并且减少氢键或电偶极相互作用能力并不会增加烃类渗透。这些观察结果排除了简单的两亲性或偶极相互作用作为界面倾向的物理基础。更有可能的是，这种倾向主要由色氨酸扁平刚性的形状决定，该形状限制了对烃核的进入，以及其π电子结构和相关的四极矩（芳香性），这些都有利于存在于静电复杂的界面环境中。
One of the ubiquitous features of membrane proteins is the preference of tryptophan and tyrosine residues for membrane surfaces that presumably arises from enhanced stability due to distinct interfacial interactions. The physical basis for this preference is widely believed to arise from amphipathic interactions related to imino group hydrogen bonding and/or dipole interactions. We have examined these and other possibilities for tryptophan's interfacial preference by using H-1 magic angle spinning (MAS) chemical shift measurements, two-dimensional (2D) nuclear Overhauser effect spectroscopy (2D-NOESY) H-1 MAS NMR, and solid state H-2 NMR to study the-interactions of four tryptophan analogues with phosphatidylcholine membranes. We find that the analogues reside in the vicinity of the glycerol group where they all cause similar modest changes in acyl chain organization and that hydrocarbon penetration was not increased by reduction of hydrogen bonding or electric dipole interaction ability. These observations rule out simple amphipathic or dipolar interactions as the physical basis for the interfacial preference. More likely, the preference is dominated by tryptophan's flat rigid shape that limits access to the hydrocarbon core and its pi electronic structure and associated quadrupolar moment (aromaticity) that favor residing in the electrostatically complex interface environment.