Solubility of amphiphiles in membranes: influence of phase properties and amphiphile head group
Solubility of amphiphiles in membranes: influence of phase properties and amphiphile head group
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DOI：
10.1016/s0006-291x(02)00905-1
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发表时间：
2002-08-23
影响因子：
3.1
通讯作者：
Vaz, WLC
中科院分区：
文献类型：
--
作者：
Estronca, LMBB;Moreno, MJ;Vaz, WLC
比较了两种极性结构相似、极性头基团不同的荧光脂质两亲体nbd -十六烷基胺和rg -十四烷基胺（或-十八烷基胺）在23°温度下，以1/50的摩尔比在脂质双分子层中的溶解度。检测的双层膜分为固相、液无序相和液有序相。nbd -十六烷基胺可溶于所有检测的双层膜相，而rg -十四烷基胺仅在液体无序相中稳定溶解。rg -十四乙胺在固体和液体有序相中的不溶性表现为两亲性物质在几天内的聚集，并研究了聚集动力学。这些两亲体在不同相中的溶解度似乎与两亲体的偶极矩（特别是极性荧光团）及其相对于膜的偶极势的取向有关。我们提出插入膜的两亲性分子（包括脂质附着蛋白）根据以下因素划分成不同的共存膜相：(1)极性结构的性质（如文献中提出的链长度、饱和程度和链分支）；(2)分子极性部分的偶极矩相对于膜偶极势的大小和取向；(3)水合力是膜表面水偶极子排列顺序的结果。(C) 2002 Elsevier Science （USA）。版权所有。
The solubilities of two fluorescent lipid amphiphiles with comparable apolar structures and different polar head groups, NBD-hexadecylamine and RG-tetradecylamine (or -octadecylamine), were compared in lipid bilayers at a molar ratio of 1/50 at 23degreesC. Bilayers examined were in the solid, liquid-disordered, or liquid-ordered phases. While NBD-hexadecylamine was soluble in all the examined bilayer membrane phases, RG-tetradecylamine was stably soluble only in the liquid-disordered phase. RG-tetradecylamine insolubility in solid and liquid-ordered phases manifests itself as an aggregation of the amphiphile over a period of several days and the kinetics of aggregation were studied. Solubility of these amphiphiles in the different phases examined seems to be related to the dipole moment of the amphiphile (in particular, of the polar fluorophore) and its orientation relative to the dipolar potential of the membrane. We propose that amphiphilic molecules inserted into membranes (including lipid-attached proteins) partition into different coexisting membrane phases based upon: (1) nature of the apolar structure (chain length, degree of saturation, and chain branching as has been proposed in the literature); (2) magnitude and orientation of the dipole moment of the polar portion of the molecules relative to the membrane dipolar potential; and (3) hydration forces that are a consequence of ordering of water dipoles at the membrane surface. (C) 2002 Elsevier Science (USA). All rights reserved.