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Modulation of poly(ethylene glycol)-induced fusion by membrane hydration: importance of interbilayer separation.

Publication ,  Journal Article
Burgess, SW; McIntosh, TJ; Lentz, BR
Published in: Biochemistry
March 17, 1992

Large unilamellar vesicles composed of lipids with different hydration properties were prepared by the extrusion technique. Vesicles were composed of dioleoylphosphatidylcholine in combination with either 0.5 mol % monooleoylphosphatidylcholine or different molar ratios of dilauroylphosphatidylethanolamine. Fusion was revealed via a fluorescence assay for contents mixing and leakage, a fluorescent lipid probe assay for membrane mixing, and quasi-elastic light scattering to detect vesicle size growth. As the percentage of poorly hydrating phosphatidylethanolamine increased, the concentration of poly(ethylene glycol) (PEG) required to induce fusion decreased. From differential scanning calorimetry studies of membrane-phase behavior and X-ray diffraction monitoring of phase structure in PEG, it was concluded that PEG did not induce a hexagonal-phase transition or lamellar-phase separation. Electron density profiles derived from X-ray diffraction studies of multi- and unilamellar vesicles indicated that the water layer between vesicles had a thickness of approximately 5 A at PEG concentrations at which vesicles were first induced to fuse. At this distance of separation, the choline headgroups from apposing bilayers are in near-molecular contact. Since pure phosphatidylcholine vesicles did not fuse at this interbilayer spacing, a reduction in the interbilayer water layer to a critical width of approximately 2 water molecules may contribute to but is not sufficient to produce PEG-mediated fusion of phospholipid membranes. Comparison of these results with other results from this laboratory also indicates that, while close contact between bilayers promotes fusion, near-molecular contact is apparently not absolutely necessary to bring about fusion. A tentative model is presented to account for these results.

Duke Scholars

Published In

Biochemistry

DOI

ISSN

0006-2960

Publication Date

March 17, 1992

Volume

31

Issue

10

Start / End Page

2653 / 2661

Location

United States

Related Subject Headings

  • X-Ray Diffraction
  • Water
  • Scattering, Radiation
  • Polyethylene Glycols
  • Phosphatidylethanolamines
  • Phosphatidylcholines
  • Membrane Fusion
  • Lipid Bilayers
  • Light
  • Fluorescent Dyes
 

Citation

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Burgess, S. W., McIntosh, T. J., & Lentz, B. R. (1992). Modulation of poly(ethylene glycol)-induced fusion by membrane hydration: importance of interbilayer separation. Biochemistry, 31(10), 2653–2661. https://doi.org/10.1021/bi00125a004
Burgess, S. W., T. J. McIntosh, and B. R. Lentz. “Modulation of poly(ethylene glycol)-induced fusion by membrane hydration: importance of interbilayer separation.Biochemistry 31, no. 10 (March 17, 1992): 2653–61. https://doi.org/10.1021/bi00125a004.
Burgess SW, McIntosh TJ, Lentz BR. Modulation of poly(ethylene glycol)-induced fusion by membrane hydration: importance of interbilayer separation. Biochemistry. 1992 Mar 17;31(10):2653–61.
Burgess, S. W., et al. “Modulation of poly(ethylene glycol)-induced fusion by membrane hydration: importance of interbilayer separation.Biochemistry, vol. 31, no. 10, Mar. 1992, pp. 2653–61. Pubmed, doi:10.1021/bi00125a004.
Burgess SW, McIntosh TJ, Lentz BR. Modulation of poly(ethylene glycol)-induced fusion by membrane hydration: importance of interbilayer separation. Biochemistry. 1992 Mar 17;31(10):2653–2661.
Journal cover image

Published In

Biochemistry

DOI

ISSN

0006-2960

Publication Date

March 17, 1992

Volume

31

Issue

10

Start / End Page

2653 / 2661

Location

United States

Related Subject Headings

  • X-Ray Diffraction
  • Water
  • Scattering, Radiation
  • Polyethylene Glycols
  • Phosphatidylethanolamines
  • Phosphatidylcholines
  • Membrane Fusion
  • Lipid Bilayers
  • Light
  • Fluorescent Dyes