Harroun Thad A, Koslowsky Martin, Nieh Mu-Ping, de Lannoy Charles-François, Raghunathan V A, Katsaras John
Steacie Institute for Molecular Sciences, National Research Council, Chalk River, Ontario K0J 1J0, Canada.
Langmuir. 2005 Jun 7;21(12):5356-61. doi: 10.1021/la050018t.
Mixtures of long- and short-chain phospholipids, specifically 14:0 and 6:0 phosphatidylcholines (DMPC and DHPC), have been used successfully in NMR studies as magnetically alignable substrates for membrane-associated proteins. However, recent publications have shown that the phase behavior of these mixtures is much more complex than originally thought. Using polarized light microscopy and small-angle neutron scattering, phase diagrams of DMPC/DHPC mixtures at molar ratios of 2, 3.2, and 5 have been determined. Generally, at temperatures below the main-chain melting transition of DMPC (T(M) = 23 degrees C), an isotropic phase of disk-like micelles is found. At high temperatures (T > 50 degrees C), a lamellar phase consisting of either multilamellar vesicles (MLV) or extended lamellae is formed, which at low lipid concentrations (e.g., MLV) coexists with an excess of water. At intermediate temperatures and lipid concentrations, a chiral nematic phase made up of worm-like micelles was observed.
长链和短链磷脂的混合物，特别是14:0和6:0磷脂酰胆碱（二肉豆蔻酰磷脂酰胆碱和二己酰磷脂酰胆碱），已成功用于核磁共振研究，作为与膜相关蛋白质的磁可排列底物。然而，最近的出版物表明，这些混合物的相行为比最初想象的要复杂得多。使用偏光显微镜和小角中子散射，已确定了摩尔比为2、3.2和5的二肉豆蔻酰磷脂酰胆碱/二己酰磷脂酰胆碱混合物的相图。一般来说，在低于二肉豆蔻酰磷脂酰胆碱主链熔化转变温度（T(M)=23℃）时，会发现盘状胶束的各向同性相。在高温（T>50℃）下，会形成由多层囊泡（MLV）或延伸片层组成的层状相，在低脂质浓度下（例如MLV），它与过量的水共存。在中间温度和脂质浓度下，观察到由蠕虫状胶束组成的手性向列相。
