Jørgensen K, Sperotto M M, Mouritsen O G, Ipsen J H, Zuckermann M J
Department of Pharmacology, University of Virginia, Charlottesville 22908.
Biochim Biophys Acta. 1993 Oct 10;1152(1):135-45. doi: 10.1016/0005-2736(93)90240-z.
A molecular interaction model is used to describe the phase diagram of two-component phospholipid bilayer membranes of saturated phospholipids, DCnPC, with different acyl-chain lengths, n = 12,14,18,20. The interaction between acyl chains of different length is formulated in terms of a hydrophobic mismatch which permits the series of binary phase diagrams to be calculated in terms of a single 'universal' interaction parameter. The properties of the model are calculated by computer-simulation techniques which not only permit determination of the specific-heat function and the phase diagram but also reveal the local structure of the mixture in the different parts of the phase diagram. The local structure is described pictorially and characterized quantitatively in terms of a correlation function. It is shown that the non-ideal mixing of lipid species due to mismatch in the hydrophobic lengths leads to a progressively increasing local ordering as the chain-length difference is increased. A pronounced local structure is found to persist deep inside the fluid phase of the mixture. The local structure is discussed in relation to the features observed in the specific-heat function, for which theoretical data, as well as experimental data obtained from differential-scanning calorimetry are presented.
一个分子相互作用模型被用于描述具有不同酰基链长度（n = 12、14、18、20）的饱和磷脂DCnPC的双组分磷脂双层膜的相图。不同长度酰基链之间的相互作用是根据疏水错配来表述的，这使得一系列二元相图能够根据单一的“通用”相互作用参数进行计算。该模型的性质通过计算机模拟技术来计算，这不仅能够确定比热函数和相图，还能揭示相图不同部分混合物的局部结构。局部结构通过相关函数进行直观描述并定量表征。结果表明，由于疏水长度不匹配导致的脂质种类的非理想混合，随着链长差异的增加，会导致局部有序性逐渐增强。在混合物的流体相中深处发现有明显的局部结构持续存在。结合比热函数中观察到的特征对局部结构进行了讨论，并给出了理论数据以及从差示扫描量热法获得的实验数据。
