The Molecular Structure of the Liquid-Ordered Phase of Lipid Bilayers

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• 作者：Alexander J. Sodt ; Michael Logan Sandar ; Klaus Gawrisch ; Richard W. Pastor ; Edward Lyman
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：January 15, 2014
• 年：2014
• 卷：136
• 期：2
• 页码：725-732
• 全文大小：453K
• ISSN：1520-5126

文摘

Molecular dynamics simulations reveal substructures within the liquid-ordered phase of lipid bilayers. These substructures, identified in a 10 渭s all-atom trajectory of liquid-ordered/liquid-disordered coexistence (L_o/L_d) are composed of saturated hydrocarbon chains packed with local hexagonal order and separated by interstitial regions enriched in cholesterol and unsaturated chains. Lipid hydrocarbon chain order parameters calculated from the L_o phase are in excellent agreement with ²H NMR measurements; the local hexagonal packing is also consistent with ¹H-MAS NMR spectra of the L_o phase, NMR diffusion experiments, and small-angle X-ray and neutron scattering. The balance of cholesterol-rich to local hexagonal order is proposed to control the partitioning of membrane components into the L_o regions. The latter have been frequently associated with formation of so-called rafts, platforms in the plasma membranes of cells that facilitate interaction between components of signaling pathways.