Reyes Mateo C, Brochon J C, Pilar Lillo M, Ulises Acuña A
Laboratoire pour l'Utilisation du Rayonnement Electromagnétique, Centre National de la Recherche Scientifique-Ministère de l'Education Nationale-Commissariat à l'Energie Atomìque, Université Paris Sud, Orsay, France.
Biophys J. 1993 Nov;65(5):2237-47. doi: 10.1016/S0006-3495(93)81257-8.
Fluid heterogeneity in lipid bilayers and shows a simple and useful method to quantify this heterogeneity. Taking advantage of the maximum entropy method, we have resolved the probe fluorescence lifetime distributions in homogeneous solutions and in single and two-component lipid bilayers at different temperatures. A precise description of the emission kinetics was obtained as a function of viscosity in the homogeneous solution and as a function of the phase composition (gel/fluid) in the lipid bilayers. These data show, unambiguously, that the same distribution pattern, with two well resolved lifetime classes, is observed both in pure solvents and in fluid bilayers. This distribution is modified during the thermotropic phase transition, with the appearance of a long lifetime component. The anisotropy experiments confirm that the amplitude of this component is proportional to the fraction of probe located in the gel phase. From this fraction we have quantified the amount of gel phase in the binary bilayer system dimyristoyl phosphatidylcholine/dipalmitoyl phosphatidylcholine and determined the thermotropic phase diagram of the mixture. This phase diagram agrees well with that calculated assuming ideal mixing of the lipids (Marbrey, S., and J.M. Sturtevant. 1976. Proc. Natl. Acad. Sci. USA. 73:862-3866).
脂质双层中的流体异质性，并展示了一种简单且有用的方法来量化这种异质性。利用最大熵方法，我们解析了在不同温度下均匀溶液以及单组分和双组分脂质双层中探针荧光寿命分布。获得了发射动力学的精确描述，它是均匀溶液中粘度的函数以及脂质双层中相组成（凝胶/流体）的函数。这些数据明确表明，在纯溶剂和流体双层中都观察到相同的分布模式，具有两个分辨良好的寿命类别。在热致相变过程中，这种分布会发生改变，出现一个长寿命组分。各向异性实验证实，该组分的幅度与位于凝胶相中的探针分数成正比。根据这个分数，我们量化了二元双层系统二肉豆蔻酰磷脂酰胆碱/二棕榈酰磷脂酰胆碱中凝胶相的量，并确定了混合物的热致相图。该相图与假设脂质理想混合计算得出的相图非常吻合（Marbrey, S., 和 J.M. Sturtevant. 1976. Proc. Natl. Acad. Sci. USA. 73:862 - 3866）。
