ISSN:
1432-1424
Keywords:
cardiolipin
;
hexagonal phase
;
lamellar phase
;
lipid polymorphism
;
phase transition
;
freeze fracture
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary 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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01870399
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