Spontaneous vesiculation of large multilamellar vesicles composed of saturated phosphatidylcholine and phosphatidylglycerol mixtures

• Published in: Biochemistry (Easton) Vol. 27; no. 24; pp. 8724 - 8730
• Main Authors: Madden, T. D, Tilcock, C. P. S, Wong, K, Cullis, P. R
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.11.1988
• Subjects: Artificial membranes and reconstituted systems; Biological and medical sciences; Calorimetry, Differential Scanning; Elasticity; Freeze Fracturing; Fundamental and applied biological sciences. Psychology; Kinetics; Light; Liposomes; Magnetic Resonance Spectroscopy; Membrane physicochemistry; Microscopy, Electron; Molecular biophysics; Osmolar Concentration; Phosphatidylcholines; Phosphatidylglycerols; Scattering, Radiation; Structure-Activity Relationship; Thermodynamics; Quasi elastic scattering; Differential scanning calorimetry; Transition temperature; Ionic strength; Liposome; Phosphatidylcholine; Phosphatidylglycerol; Freeze etching; Artificial membrane; NMR spectrometry
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi00424a006

The influence of temperature and ionic strength on the vesiculation properties of large multilamellar vesicles containing various proportions of dimyristoylphosphatidylglycerol has been investigated. It is shown that at low ionic strengths preformed large multilamellar vesicles composed of dimyristoylphosphatidylcholine and dimyristoylphosphatidylglycerol (7:3) on incubation at the gel to liquid-crystalline transition temperature (Tc approximately 23 degrees C) spontaneously vesiculate to form predominantly unilamellar systems with a mean diameter of 120 nm. Such vesiculation is not observed for incubations at temperatures appreciably above or below Tc, and is also inhibited by higher ionic strengths. Stable large multilamellar vesicles are formed, however, in systems containing the dioleoyl species of phosphatidylcholine or phosphatidylglycerol and also for dimyristoylphosphatidylcholine/dimyristoylphosphatidylserine mixtures. The vesiculation properties of dimyristoylphosphatidylcholine/dimyristoylphosphatidylglycerol mixtures, therefore, appear to reflect an instability in the region of the Tc driven by surface potential effects which are specific for the glycerol headgroup.