Rilfors L, Eriksson P O, Arvidson G, Lindblom G
Biochemistry. 1986 Nov 18;25(23):7702-11. doi: 10.1021/bi00371a063.
Several lipid-water mixtures form phases that give rise to freeze-fracture replicas exhibiting three-dimensional regular arrays of closely packed globular elements, often called "lipidic particles". These phases have often been poorly classified with respect to long-range organization and symmetry and have in most cases been asserted to be built up by closed lipid aggregates, such as reversed micelles. However, studies of phases giving rise to the above-mentioned freeze-fracture replicas, with X-ray diffraction and the nuclear magnetic resonance pulsed field gradient diffusion technique, have revealed that they are cubic liquid-crystalline phases and with one exception bicontinuous phases, i.e., cubic phases in which both the hydrocarbon and the water regions are continuous. Up to now the only known exception is a cubic phase composed of closed rod-shaped micelles of the normal type. Thus it is not possible to decide from a freeze-fracture image of a cubic phase, showing three-dimensional arrays of "lipidic particles", if the phase is bicontinuous or composed of closed lipid aggregates. Hitherto, it has not been shown that a biological membrane lipid-water system is able to form a cubic liquid-crystalline phase consisting of reversed micelles. The existence of such a phase is also improbable considering the location in the phase diagrams of cubic phases formed by biological membrane lipid-water systems.
几种脂质 - 水混合物形成的相，会产生冷冻蚀刻复制品，呈现出紧密堆积的球状元素的三维规则阵列，这些球状元素通常被称为“脂质颗粒”。就长程组织和对称性而言，这些相的分类往往很差，并且在大多数情况下被认为是由封闭的脂质聚集体（如反胶束）构成的。然而，通过X射线衍射和核磁共振脉冲场梯度扩散技术对产生上述冷冻蚀刻复制品的相进行研究后发现，它们是立方液晶相，且除了一种情况外都是双连续相，即烃区和水区都是连续的立方相。到目前为止，唯一已知的例外是由正常类型的封闭棒状胶束组成的立方相。因此，从显示“脂质颗粒”三维阵列的立方相的冷冻蚀刻图像中，无法确定该相是双连续相还是由封闭脂质聚集体组成。迄今为止，尚未证明生物膜脂质 - 水体系能够形成由反胶束组成的立方液晶相。考虑到生物膜脂质 - 水体系形成的立方相在相图中的位置，这种相的存在也不太可能。
