Mély-Goubert B, Freedman M H
Biochim Biophys Acta. 1980 Sep 18;601(2):315-27. doi: 10.1016/0005-2736(80)90536-2.
Experiments have been designed to challenge the use of stedy-state fluorescence polarizaiton with 1,6-diphenyl-1,3,5-hexatriene as an evaluator of the fluidity of cell plasma membranes. We used paraffinic systems, of defined structure and composition (liquid paraffin, soap bilayers and phospholipid liposomes--with and without incorporated proteins), to demonstrate that corresponding polarizaiton values cannot be interpreted in terms of the overall fluidity of the labeled medium. In homogeneous structured paraffinic media (lipid bilayers), knowledge of the location of the probe is essential for a consistent interpretation of the observed fluorescence polarization. Due to the highly polarizable electronic structure of the diphenylhexatriene molecule, the presence of heterogeneities with potential sites for interaction (e.g., C18-coated Si particles, albumin molecules, etc.) can lead to relatively high polarization values, even in isotropic media. In cellular systems, translocation experiments from labeled cells to added proteins show a rather localized peripheral distribution of the probe as well as its high affinity for hydrophobic sites of proteins. This and other arguments presented here suggest that although cellular polarization values represent an intricate average over all labeled hydrophobic regions of the cell (phospholipid bilayers, membrane proteins, etc.), these values might reflect, to a large extent, interactions of the probe with proteins from the inner periphery of the cell.
已经设计了一些实验来质疑使用1,6 - 二苯基 - 1,3,5 - 己三烯作为细胞质膜流动性评估指标的稳态荧光偏振法。我们使用了具有确定结构和组成的链烷烃体系（液体石蜡、皂双层和磷脂脂质体——有或没有掺入蛋白质），以证明相应的偏振值不能根据标记介质的整体流动性来解释。在均匀结构的链烷烃介质（脂质双层）中，了解探针的位置对于一致地解释观察到的荧光偏振至关重要。由于二苯基己三烯分子具有高度可极化的电子结构，即使在各向同性介质中，存在具有潜在相互作用位点的异质性（例如C18包覆的硅颗粒、白蛋白分子等）也会导致相对较高的偏振值。在细胞体系中，从标记细胞到添加蛋白质的转运实验表明，探针呈现出相当局部的外周分布以及它对蛋白质疏水位点的高亲和力。本文提出的这一点及其他观点表明，尽管细胞偏振值代表了细胞所有标记疏水区域（磷脂双层、膜蛋白等）的复杂平均值，但这些值可能在很大程度上反映了探针与细胞内周蛋白质的相互作用。
