Studies on membrane fusion. 1. Interactions of pure phospholipid membranes and the effect of myristic acid, lysolecithin, proteins and dimethylsulfoxide

D. Papahadjopoulos, S. Hui, W. J. Vail, George Poste

Research output: Contribution to journalArticle

138 Citations (Scopus)

Abstract

The interaction and mixing of membrane components in sonicated unilamellar vesicles and also non-sonicated multilamellar vesicles prepared from highly purified phospholipids suspended in NaCl solutions has been examined. Electron microscopy and differential scanning calorimetry were used to characterize the extent and kinetics of mixing of membrane components between different vesicle populations. No appreciable fusion was detected between populations of non-sonicated phospholipid vesicles incubated in aqueous salt (NaCl) solutions. Mixing of vesicle membrane components via diffusion of phospholipid molecules between vesicles was observed in populations of negatively charged phosphatidylglycerol vesicles but similar exchange diffusion was not detected in populations of neutral phosphatidylcholine vesicles. Incubation of sonicated vesicle populations at temperatures close to or above the phospholipid transition temperature resulted in an increase in vesicle size and mixing of vesicle membrane components as determined by a gradual change in the thermotropic properties of the mixed vesicle population. The interaction of purified phospholipid vesicles was also examined in the presence of myristic acid and lysolecithin. Our results indicate that while these agents enhance mixing of vesicle membrane components, in most cases mixing probably proceeds via diffusion of phospholipid molecules rather than by fusion of entire vesicles. Increased mixing of vesicle membrane components was also produced when vesicles were prepared containing a purified hydrophobic protein (myelin proteolipid apoprotein) or were incubated in the presence of dimethylsulfoxide. In these two systems, however, the evidence suggests that mixing of membrane components results from the fusion of entire vesicles.

Original languageEnglish (US)
Pages (from-to)245-264
Number of pages20
JournalBBA - Biomembranes
Volume448
Issue number2
DOIs
StatePublished - Oct 5 1976
Externally publishedYes

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Lysophosphatidylcholines
Membrane Fusion
Myristic Acid
Dimethyl Sulfoxide
Phospholipids
Fusion reactions
Membranes
Proteins
Population
Proteolipids
Unilamellar Liposomes
Phosphatidylglycerols
Apoproteins
Transition Temperature
Differential Scanning Calorimetry
Molecules
Myelin Sheath
Phosphatidylcholines
Electron Microscopy
Electron microscopy

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Cell Biology
  • Medicine(all)

Cite this

Studies on membrane fusion. 1. Interactions of pure phospholipid membranes and the effect of myristic acid, lysolecithin, proteins and dimethylsulfoxide. / Papahadjopoulos, D.; Hui, S.; Vail, W. J.; Poste, George.

In: BBA - Biomembranes, Vol. 448, No. 2, 05.10.1976, p. 245-264.

Research output: Contribution to journalArticle

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