MINIMAL SURFACE-TENSION, SQUEEZE-OUT AND TRANSITION-TEMPERATURES OF BINARY-MIXTURES OF DIPALMITOYLPHOSPHATIDYLCHOLINE AND UNSATURATED PHOSPHOLIPIDS
MINIMAL SURFACE-TENSION, SQUEEZE-OUT AND TRANSITION-TEMPERATURES OF BINARY-MIXTURES OF DIPALMITOYLPHOSPHATIDYLCHOLINE AND UNSATURATED PHOSPHOLIPIDS
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DOI：
10.1016/0005-2760(89)90072-6
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发表时间：
1989-03-14
期刊：
影响因子：
--
通讯作者：
MAZURE, A
中科院分区：
文献类型：
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作者：
EGBERTS, J;SLOOT, H;MAZURE, A
荧光偏振（FP）的测量和表面张力（ST）的实验进行，以确定磷脂混合物的凝胶到液晶的转变或熔融温度。FP-温度图显示二棕榈酰磷脂酰胆碱（DPPC）的主要转变温度为41 ℃。DPPC与磷脂酰肌醇（PI）、磷脂酰甘油（PG）和磷脂酰胆碱（PC）的7：3和9：1二元混合物的主要转变温度分别为32 - 36 ℃和37 - 39 ℃。DPPC单层的最小表面张力在40 ℃迅速增加，表明这是这些单层熔化的转变温度。该值与荧光偏振测量观察到的DPPC的主要转变温度密切一致。几乎所有的混合物的单分子膜的熔融温度都高于过渡开始时的温度，这表明优先挤出的不饱和组分和富集的单分子膜与DPPC。然而，无论是7：3 DPPC/PC还是DPPC/PG混合物都不能在高于30 ℃的温度下承受高表面压力，而DPPC/PG（9：1）的单层在高于35 ℃的温度下变成流体。不饱和磷脂的优先挤出在7：3和9：1 DPPC/PI混合物中特别有效。这些单层在39 - 40 ℃开始熔融，这分别高于它们的主要转变温度32和37 ℃，并且接近DPPC的熔融温度。优先挤出是人工肺表面活性剂的基本要求。因此，通过确定单层熔融温度来估计这种现象对于区分在体温下是有效表面活性剂的混合物和不太有效的混合物是有用的。
Fluorescence polarization (FP) measurements and surface tension (ST) experiments were performed to determine the gel-to-liquid-crystal transition or melting temperature of phospholipid mixtures. The FP-temperature diagrams showed main transition temperatures of 41.degree.C for dipalmitoylphosphatidylcholine (DPPC). The 7:3 and 9:1 binary mixtures of DPPC and phosphatidylinositol (PI), phosphatidylglycerol (PG) and phosphatidylcholine (PC) had main transition temperatures of, respectively, 32-36.degree.C and 37-39.degree.C. The minimal surface tension of DPPC monolayers increased rapidly at 40.degree.C, suggesting that this was the transition temperature for the melting of these monolayers. This value was in close accordance with the main transition temperature of DPPC, observed with the fluorescence polarization measurements. Melting temperatures of monolayers were higher for almost all mixtures than the temperatures at which the transition started, indicating preferential squeeze out of the unsaturated component and enrichment of the monolayer with DPPC. However, neither the 7:3 DPPC/PC nor the DPPC/PG mixtures could withstand high surface pressures at temperatures above 30.degree.C, whereas monolayers of DPPC/PG (9:1) became fluid at temperatures above 35.degree.C. Preferential squeeze-out of the unsaturated phospholipid was especially effective in both the 7:3 and 9:1 DPPC/PI mixtures. These monolayers started to melt at 39-40.degree.C, which is above their main transition temperatures of, respectively, 32 and 37.degree.C, and which approximate the melting temperature of DPPC. Preferential squeeze-out is essential for an artificial lung surfactant. The estimation of this phenomenon by determining the monolayer melting temperatures is therefore useful for distinguishing between mixtures which are effective surfactants at body temperature and those which are less effective.