Melting Behaviour of Cell Death Lipids

ORAL

Abstract

Sphingomyelin is a major lipid constituent of mammalian cell plasma membranes. It is converted into ceramide during programmed cell death. It is hypothesized that this conversion induces a structural change in membranes that is responsible for downstream signaling. To characterize these structural changes, deuterium nuclear magnetic resonance spectroscopy is used to create a concentration-temperature phase diagram of palmitoyl sphingomyelin:ceramide multilamellar vesicles in excess water between 0-40 mol\% ceramide and 25-80$^{\circ}$C. The two lipids are fully miscible at high temperatures and at 40 mol\% ceramide. A variety of solid-liquid coexistence phase behavior is observed at lower concentrations. With increasing ceramide content, a gel phase is observed at progressively higher temperatures, implying that at physiological temperature, ceramide may increase the gel phase propensity of cell membranes.

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Authors

  • Sherry Leung

    Simon Fraser University

  • Anthony Colaprete

    Triumf, Texas A\&M University, Tel Aviv University, TRIUMF, Simon Fraser University, Dept. of Physics, SFU, BC, Canada, Department of Physics and Astronomy, University of British Columbia, Cavendish Laboratory, University of Cambridge, Department of Physics, Simon Fraser University, University of British Columbia, University of Wisconsin-Madison, Brookhaven National Laboratory, Los Alamos National Laboratory, Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Korea, Department of Physics, Oregon State University, Corvallis, OR 97331-6507, Imago Scientific Instruments Corp., Department of Physics, Simon Fraser University, 8888 University Dr., Burnaby, BC, V5A 1S6 Canada, Linfield College, PNNL, University of Washington, University of Victoria, IUPUI1, Wabash, IUPUI2, Environmental Biotechnology Institute, University of Idaho, Moscow ID 83843, Physics Department, University of Idaho, Moscow ID 83843, Environmental Biotechnology Institute, University of Idaho, Moscow, ID 83844, Physics Department, University of Idaho, Moscow, Idaho 83844, TRIUMF / UBC, 5CSNSM-IN2P3-CNRS, Universit\'e Paris 11, University of Manitoba, Texas A\&M, U. Manitoba, Tel Aviv U., U. British Columbia, Universidad de Pa\'is Vasco, Department of Physics, University of Idaho, Moscow, Idaho 83844-0903, University of Idaho, Boise State University, Idaho State University, NASA Ames Research Center

  • Felix Goni

    Universidad de Pa\'is Vasco

  • Jenifer Thewalt

    Simon Fraser University