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Separation of liquid phases in giant vesicles of ternary mixtures of phospholipids and cholesterol (2003)
| Venue: | Biophys. J |
| Citations: | 74 - 2 self |
BibTeX
@ARTICLE{Veatch03separationof,
author = {Sarah L. Veatch and Sarah L. Keller},
title = {Separation of liquid phases in giant vesicles of ternary mixtures of phospholipids and cholesterol},
journal = {Biophys. J},
year = {2003},
pages = {3074--3083}
}
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Abstract
ABSTRACT We use fluorescence microscopy to directly observe liquid phases in giant unilamellar vesicles. We find that a long list of ternary mixtures of high melting temperature (saturated) lipids, low melting temperature (usually unsaturated) lipids, and cholesterol produce liquid domains. For one model mixture in particular, DPPC/DOPC/Chol, we have mapped phase boundaries for the full ternary system. For this mixture we observe two coexisting liquid phases over a wide range of lipid composition and temperature, with one phase rich in the unsaturated lipid and the other rich in the saturated lipid and cholesterol. We find a simple relationship between chain melting temperature and miscibility transition temperature that holds for both phosphatidylcholine and sphingomyelin lipids. We experimentally cross miscibility boundaries both by changing temperature and by the depletion of cholesterol with b-cyclodextrin. Liquid domains in vesicles exhibit interesting behavior: they collide and coalesce, can finger into stripes, and can bulge out of the vesicle. To date, we have not observed macroscopic separation of liquid phases in only binary lipid mixtures.
Keyphrases
liquid phase ternary mixture giant vesicle model mixture wide range phase rich high melting temperature dppc dopc chol giant unilamellar vesicle lipid composition macroscopic separation unsaturated lipid miscibility transition temperature saturated lipid long list phase boundary sphingomyelin lipid low melting temperature binary lipid mixture fluorescence microscopy miscibility boundary full ternary system simple relationship interesting behavior liquid domain
