Effect of Cationic Lipids in the Formation of Asymmetries in Supported Bilayers

We have studied the formation of a supported bilayer containing both cationic and zwitterionic lipids by fusion of small unilamellar vesicles (SUV) onto the solid surface at low salt conditions using a combination of attenuated total reflection infrared (ATR-IR) and deuterium NMR spectroscopy with m...

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Bibliographic Details
Published in:Biophysical journal 1999-05, Vol.76 (5), p.2600-2605
Main Authors: Käsbauer, M., Junglas, M., Bayerl, T.M.
Format: Article
Language:English
Subjects:
Biology
Biophysical Phenomena
Biophysics
Calorimetry, Differential Scanning
Cations
Lipid Bilayers - chemistry
Lipids
Liposomes - chemistry
Magnetic Resonance Spectroscopy
Membrane Fusion
Molecules
Spectrophotometry, Infrared
Static Electricity
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Summary:We have studied the formation of a supported bilayer containing both cationic and zwitterionic lipids by fusion of small unilamellar vesicles (SUV) onto the solid surface at low salt conditions using a combination of attenuated total reflection infrared (ATR-IR) and deuterium NMR spectroscopy with microcalorimetry. The data suggest that a significant cationic lipid asymmetry between the outer (distal) and the inner (proximal) monolayer of a supported bilayer results under conditions of prolonged incubation times of the solid support with the SUV coating solution. For a SUV composition of DPPC/DHDAB (4:1) we observed an enrichment of the cationic component in the proximal monolayer of up to 200% compared to the distal monolayer after 12 h incubation. It is suggested that the electrostatic potential arising from the solid surface is the driving force for the creation of this asymmetry by means of directed flip-flop between the monolayers and/or by temporary fusion between SUV from the bulk with the supported bilayer.
ISSN:0006-3495
1542-0086
DOI:10.1016/S0006-3495(99)77412-6