title: Docosahexaenoic acid promotes micron scale liquid-ordered domains. A comparison study of docosahexaenoic versus oleic acid containing phosphatidylcholine in raft-like mixtures.
abstract: The understanding of the functional role of the lipid diversity in biological membranes is a major challenge. Lipid models have been developed to address this issue by using lipid mixtures generating liquid-ordered (Lo)/liquid-disordered (Ld) immiscibility. The present study examined mixtures comprising Egg sphingomyelin (SM), cholesterol (chol) and phosphatidylcholine (PC) either containing docosahexaenoic (PDPC) or oleic acid (POPC). The mixtures were examined in terms of their capability to induce phase separation at the micron- and nano-scales. Fluorescence microscopy, electron spin resonance (ESR), X-ray diffraction (XRD) and calorimetry methods were used to analyze the lateral organization of the mixtures. Fluorescence microscopy of giant vesicles could show that the temperature of the micron-scale Lo/Ld miscibility is higher for PDPC than for POPC ternary mixtures. At 37°C, no micron-scale Lo/Ld phase separation could be identified in the POPC containing mixtures while it was evident for PDPC. In contrast, a phase separation was distinguished for both PC mixtures by ESR and XRD, indicative that PDPC and POPC mixtures differed in micron vs nano domain organization. Compared to POPC, the higher line tension of the Lo domains observed in PDPC mixtures is assumed to result from the higher difference in Lo/Ld order parameter rather than hydrophobic mismatch.
authors.affiliation: Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria.
authors.forename: R
authors.initials: R
authors.lastname: Georgieva
authors.affiliation: Universite Pierre et Marie Curie-Paris 6, INSERM U893, CHU St. Antoine, 27 rue Chaligny, 75012 Paris, France.
authors.forename: C
authors.initials: C
authors.lastname: Chachaty
authors.affiliation: Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria.
authors.forename: R
authors.initials: R
authors.lastname: Hazarosova
authors.affiliation: UMR 7203, INSERM ERL 1057 - Bioactive Molecules Laboratory, Pierre et Marie Curie University, Paris, France; Department of Psychiatry, Hôpital Saint-Antoine, AP-HP, Paris, France.
authors.forename: C
authors.initials: C
authors.lastname: Tessier
authors.affiliation: UMR 7203, INSERM ERL 1057 - Bioactive Molecules Laboratory, Pierre et Marie Curie University, Paris, France; Department of Psychiatry, Hôpital Saint-Antoine, AP-HP, Paris, France.
authors.forename: P
authors.initials: P
authors.lastname: Nuss
authors.affiliation: Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria.
authors.forename: A
authors.initials: A
authors.lastname: Momchilova
authors.affiliation: Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria. Electronic address: gstaneva@obzor.bio21.bas.bg.
authors.forename: G
authors.initials: G
authors.lastname: Staneva
mesh_terms: D000818:Animals; D002152:Calorimetry, Differential Scanning; D004281:Docosahexaenoic Acids / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D021962:Membrane Microdomains / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D019301:Oleic Acid / Q000737:chemistry*; D044367:Phase Transition; D010713:Phosphatidylcholines / Q000737:chemistry*; D013816:Thermodynamics; D044366:Transition Temperature; D014961:X-Ray Diffraction
chemical_list: D010713:Phosphatidylcholines; D004281:Docosahexaenoic Acids; D019301:Oleic Acid
keywords: Docosahexaenoic acid; Liquid-ordered phase; Oleic acid; PUFA; Raft