Smaby J M, Brockman H L
Biophys J. 1985 Nov;48(5):701-7. doi: 10.1016/S0006-3495(85)83828-5.
The miscibility of 1-palmitoyl-2-oleoyl phosphatidylcholine with triolein, 1,2-diolein, 1,3-diolein, 1(3)-monoolein, oleyl alcohol, methyl oleate, oleic acid, and oleyl cyanide (18:1 lipids) was studied at the argon-water interface. The isothermal phase diagrams for the mixtures at 24 degrees were characterized by two compositional regions. At the limit of miscibility with lower mol fractions of 18:1 lipid, the surface pressure was composition-independent, but above a mixture-specific stoichiometry, surface pressure at the limit of miscibility was composition-dependent. From the two-dimensional phase rule, it was determined that at low mol fractions of 18:1 lipids, the surface consisted of phospholipid and a preferred packing array or complex of phospholipid and 18:1 lipid, whereas, above the stoichiometry of the complex, the surface phase consisted of complex and excess 18:1 lipids. In both regions of the phase diagram, mixing along the phase boundary was apparently ideal allowing application of an equation of state described earlier (J. M. Smaby and H. L. Brockman, 1984, Biochemistry, 23:3312-3316). From such analysis, apparent partial molecular areas and hydrations for phospholipid, complex, and 18:1 lipid were obtained. Comparison of these calculated parameters for the complexed and uncomplexed states shows that the aliphatic moieties behave independently of polar head group. The transition of each 18:1 chain to the complexed state involves the loss of about one interfacial water molecule and its corresponding area. For 18:1 lipids with more than one chain another two water molecules per additional chain are present in both states but contribute little to molecular area. In contrast to 18:1 lipids, the phospholipid area and hydration change little upon complexation. The uniformity of chain packing and hydration behavior among 18:1 lipid species contrasts with complex stoichiometries that vary from 0.04 to 0.65. This suggests that the stoichiometry of the preferred packing array is determined by interactions involving the more polar moieties of the 18:1 lipids and the phospholipid.
在氩 - 水界面研究了1 - 棕榈酰 - 2 - 油酰磷脂酰胆碱与三油精、1,2 - 二油精、1,3 - 二油精、1(3)-单油精、油醇、油酸甲酯、油酸和油基氰化物（18:1脂质）的混溶性。24摄氏度下混合物的等温相图由两个组成区域表征。在与较低摩尔分数的18:1脂质混溶的极限处，表面压力与组成无关，但高于混合物特定的化学计量比时，混溶极限处的表面压力与组成有关。根据二维相律确定，在低摩尔分数的18:1脂质时，表面由磷脂以及磷脂和18:1脂质的优选堆积阵列或复合物组成，而在复合物的化学计量比之上，表面相由复合物和过量的18:1脂质组成。在相图的两个区域中，沿相边界的混合显然是理想的，这使得可以应用先前描述的状态方程（J. M. Smaby和H. L. Brockman，1984年，《生物化学》，23:3312 - 3316）。通过这种分析，获得了磷脂、复合物和18:1脂质的表观偏摩尔面积和水合作用。对复合态和非复合态这些计算参数的比较表明，脂肪族部分的行为独立于极性头部基团。每个18:1链转变为复合态涉及损失约一个界面水分子及其相应面积。对于具有多个链的18:1脂质，两种状态下每条额外的链还存在另外两个水分子，但对分子面积贡献不大。与18:1脂质相反，复合时磷脂面积和水合作用变化很小。18:1脂质种类之间链堆积和水合行为的均匀性与化学计量比从0.04到0.65变化的复合物形成对比。这表明优选堆积阵列的化学计量比由涉及18:1脂质和磷脂的极性更强部分的相互作用决定。
