Borovjagin V L, Vergara J A, McIntosh T J
J Membr Biol. 1982;69(3):199-212. doi: 10.1007/BF01870399.
The addition of calcium to suspensions of egg phosphatidylcholine and cardiolipin converts multiwalled liposomes to the hexagonal (HII) phase (Rand, R.P., Sengupta, S. (1972) Biochim. Biophys. Acta 255:484-492). We have studied this lamellar to hexagonal phase transition by freeze-fracture, thin-section electron microscopy, and X-ray diffraction and have morphologically characterized the intermediate stages. The first step in the transition involves the invagination and fusion of bilayers, marked by the appearance of lipidic intramembrane particles and "crater-like" indentations, as the large liposomes are converted to smaller flattened and elongated vesicles. The next step is the formation of tightly packed hexagonal arrays of tubules, each tubule being about 11 to 15 nm in diameter. These tubules are filled with fluid and a lipid bilayer forms the wall of each cylinder. Finally this tubular bilayer phase is converted to the hexagonal (HII) phase, where the distance between tubes is 5.5 to 7.5 nm.
向鸡蛋磷脂酰胆碱和心磷脂悬浮液中添加钙会使多层脂质体转变为六方（HII）相（兰德，R.P.，森古普塔，S.（1972年）《生物化学与生物物理学报》255:484 - 492）。我们通过冷冻断裂、超薄切片电子显微镜和X射线衍射研究了这种从层状到六方相的转变，并对中间阶段进行了形态学表征。转变的第一步涉及双层膜的内陷和融合，其标志是脂质膜内颗粒和“火山口状”凹陷的出现，此时大脂质体转变为较小的扁平且细长的囊泡。下一步是形成紧密排列的六方管状阵列，每个小管直径约为11至15纳米。这些小管充满液体，脂质双层形成每个圆柱体的壁。最后，这种管状双层相转变为六方（HII）相，此时管间距离为5.5至7.5纳米。
