Lindblom G, Brentel I, Sjölund M, Wikander G, Wieslander A
Biochemistry. 1986 Nov 18;25(23):7502-10. doi: 10.1021/bi00371a037.
A basis for the reorganization of the bilayer structure in biological membranes is the different aggregate structures formed by lipids in water. The phase equilibria of all individual lipids and several in vivo polar lipid mixtures from acyl chain modified membranes of Acholeplasma laidlawii were investigated with different NMR techniques. All dioleoyl (DO) polar lipids, except monoglucosyldiglyceride (MGDG), form lamellar liquid crystalline (L alpha) phases only. The phase diagram of DOMGDG reveals reversed cubic (III), reversed hexagonal (HII), and L alpha phases. In mixtures of DOMGDG and dioleoyldiglycosyldiglyceride (DODGDG), the formation of an III (or HII) phase is enhanced by DOMGDG and low hydration or high temperatures. For in vivo mixtures of all polar DO lipids, a transition from an L alpha to an III phase is promoted by low hydration or high temperatures (50 degrees C). The phospholipids are incorporated in this III phase. Likewise, III and HII phases are formed at similar temperatures in a series of in vivo mixtures with different extents of acyl chain unsaturation. However, their melting temperatures (Tm) vary in an expected manner. All cubic and hexagonal phases, except the III phase with DOMGDG, exist in equilibrium with excess water. The maximum hydration of MGDG and DGDG is similar and increases with acyl chain unsaturation but is substantially lower than that for, e.g., phosphatidylcholine. The translational diffusion of the lipids in the cubic phases is rapid, implying bicontinuous structures. However, their appearances in freeze-fracture electron microscope pictures are different. The III phase of DOMGDG belongs to the Ia3d space group.(ABSTRACT TRUNCATED AT 250 WORDS)
生物膜双层结构重组的一个基础是脂质在水中形成的不同聚集结构。利用不同的核磁共振技术研究了来自莱氏无胆甾原体酰基链修饰膜的所有单一脂质以及几种体内极性脂质混合物的相平衡。除单葡萄糖二甘油酯（MGDG）外，所有二油酰（DO）极性脂质仅形成层状液晶（Lα）相。DOMGDG的相图显示出反转立方相（III）、反转六方相（HII）和Lα相。在DOMGDG和二油酰二糖基二甘油酯（DODGDG）的混合物中，DOMGDG以及低水合度或高温会增强III（或HII）相的形成。对于所有极性DO脂质的体内混合物，低水合度或高温（50摄氏度）会促使从Lα相转变为III相。磷脂被整合到这个III相中。同样，在一系列具有不同酰基链不饱和度的体内混合物中，III相和HII相在相似温度下形成。然而，它们的熔点（Tm）以预期的方式变化。除了与DOMGDG形成的III相外，所有立方相和六方相都与过量水处于平衡状态。MGDG和DGDG的最大水合度相似，且随酰基链不饱和度增加，但远低于例如磷脂酰胆碱的最大水合度。脂质在立方相中的平移扩散很快，这意味着是双连续结构。然而，它们在冷冻断裂电子显微镜图片中的外观不同。DOMGDG的III相属于Ia3d空间群。（摘要截于250字）
