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Egg-Sphingomyelin and Cholesterol Form a Stoichiometric Molecular Complex in Bilayers of Egg-Phosphatidylcholine

DOI: 10.1021/jp107490a DOI Help

Authors: Peter J. Quinn (King's College London) , Claude Wolf (Universite Pierre et Marie Curie-Paris 6)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: The Journal Of Physical Chemistry B , VOL 114 (47) , PAGES 15536 - 15545

State: Published (Approved)
Published: December 2010
Diamond Proposal Number(s): 764

Abstract: Sphingomyelin and cholesterol are membrane lipids that interact to form liquid-ordered phase believed to act as a platform for the organization of signaling proteins. We report analyses of synchrotron X-ray powder diffraction patterns recorded from aqueous dispersions of ternary mixtures of sphingomyelin and phosphatidylcholine from egg yolk and cholesterol to investigate how cholesterol distributes between the two phospholipids. In the absence of cholesterol the two phospholipids are immiscible between 20 and 50 °C. Addition of up to 22 mol % cholesterol to equimolar mixtures of the phospholipids results in partition of some sphingomyelin into a phosphatidylcholine phase at 37 °C. Increased proportions of cholesterol result in partition of the excess cholesterol into the phosphatidylcholine phase which is in equilibrium with a stoichiometric complex of 1.7:1, sphingomyelin:cholesterol. The molecular order of the complex may explain the basis upon which proteins are assembled within the membrane raft.

Subject Areas: Biology and Bio-materials

Instruments: I22-Small angle scattering & Diffraction

Added On: 25/07/2012 11:50

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