Matubayasi N, Shigematsu T, Iehara T, Kamaya H, Ueda I
J Membr Biol. 1986;90(1):37-42. doi: 10.1007/BF01869684.
Miscibility among phospholipids with different lipid chain-lengths or with different head groups has attracted a number of research efforts because of its significance in biological membrane structure and function. The general consensus about the miscibility of phosphatidylcholines with varying lipid chain-lengths appears to be that binary mixtures of phospholipids with a difference of two carbon atoms in the lipid chain mix well at the main phase transition. Miscibility between phosphatidylcholines with differences of four carbon atoms appears to be inconclusive. Previous reports on the phase transition of binary phospholipid mixtures are concerned mainly with multilamellar vesicles and are mostly limited to the main transition. In the present study, unilamellar vesicles were used and miscibility in binary systems between dimyristoyl-, dipalmitoyl- and distearoyl-phosphatidylcholines at pretransition as well as main transition temperatures was evaluated by constructing phase diagrams. Two methods were used to monitor the phase transitions: differential scanning microcalorimetry and optical absorbance methods. The optical method has the advantage that unilamellar vesicles of dilute phospholipid concentrations can be used. The liquidus and solidus phase boundaries were determined by the onset temperature of heating and cooling scans, respectively, because the completion temperature of a phase transition has no meaning in binary solutions. Dimyristoyl- and distearoyl-phosphatidylcholines, where the difference in the lipid chain-length is four carbon atoms, mixed well even at pretransition temperature.
不同脂链长度或不同头部基团的磷脂之间的混溶性因其在生物膜结构和功能中的重要性而吸引了众多研究。关于不同脂链长度的磷脂酰胆碱混溶性的普遍共识似乎是，脂链相差两个碳原子的磷脂二元混合物在主相变时能很好地混合。脂链相差四个碳原子的磷脂酰胆碱之间的混溶性似乎尚无定论。先前关于二元磷脂混合物相变的报道主要涉及多层囊泡，且大多局限于主相变。在本研究中，使用了单层囊泡，并通过构建相图来评估二肉豆蔻酰基 -、二棕榈酰基 - 和二硬脂酰基 - 磷脂酰胆碱在预相变以及主相变温度下二元体系中的混溶性。使用了两种方法来监测相变：差示扫描量热法和光吸收法。光学方法的优点是可以使用稀磷脂浓度的单层囊泡。液相线和固相线的相界分别通过加热和冷却扫描的起始温度来确定，因为在二元溶液中相变的完成温度没有意义。脂链长度相差四个碳原子的二肉豆蔻酰基和二硬脂酰基磷脂酰胆碱即使在预相变温度下也能很好地混合。
