Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1945635 | Biochimica et Biophysica Acta (BBA) - Biomembranes | 2007 | 10 Pages |
Abstract
Phase diagrams of 3-component lipid bilayer mixtures containing cholesterol reveal major differences among the different types of lipids. Here we report that mixtures of cholesterol together with POPC and a high-melting temperature PC or sphingomyelin show different phase behavior from similar mixtures that contain DOPC or di-phytanoyl-PC instead of POPC. In particular, only one region of macroscopic phase coexistence occurs with POPC, a region of coexisting liquid disordered and solid phases, {Lα + Lβ}. Fluorescence microscopy imaging is useful for these studies, but is subject to artifactual light-induced domain formation, as reported by Ayuyan and Cohen [A.G. Ayuyan, F.S. Cohen, Lipid peroxides promote large rafts: Effects of excitation of probes in fluorescence microscopy and electrochemical reactions during vesicle formation, Biophys. J. 91 (2006) 2172-2183.]. This artifact can be attenuated by decreased illumination and low dye concentration. The use of the free radical scavenger n-propyl gallate can reduce the artifact, but this molecule enters the bilayer and itself perturbs the phase behavior. We suggest that the light-induced domain separation artifact might actually arise from pre-existing lipid clusters that are induced to coalesce, and therefore indicates highly nonrandom mixing of the lipid components.
Keywords
NPGDLPC2-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-1-hexadecanoyl-sn-glycero-3-phosphocholineDOPGDOPCRSEPoPCDSPCDSPGSOPC1-Stearoyl-2-Oleoyl-sn-Glycero-3-PhosphocholineGUVDPPCTLC1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine1,2-dilauroyl-sn-glycero-3-phosphocholine1,2-dioleoyl-sn-glycero-3-phosphocholine1,2-dipalmitoyl-sn-glycero-3-phosphocholine1,2-distearoyl-sn-glycero-3-phosphocholinen-Propyl gallateAntioxidantsphingomyelinFluorescence resonance energy transferFRETPhoto-inducedGiant unilamellar vesicleLiquid-ordered phaseLiquid-disordered phaseLipid peroxidationthin-layer chromatography
Related Topics
Life Sciences
Biochemistry, Genetics and Molecular Biology
Biochemistry
Authors
Jiang Zhao, Jing Wu, Huilin Shao, Fanrong Kong, Nieraj Jain, Geoffrey Hunt, Gerald Feigenson,