Membrane Biophysics

Polyunsaturated chains have a higher density near the lipid water interface of membrane while saturated chains are higher in the bilayer center. The assymetry of the distribution is smaller for lipids with n-6 DPA compared to n-3 DHA. Quantum mechanical (QM) calculations of the torsional energy surface for rotation about vinyl-methylene bonds reveal low barriers to rotation, indicating an intrinsic propensity toward flexibility. A 16 ns molecular dynamics (MD) simulation of a 1-stearoyl-2-docosahexaenoyl-sn-glyerco-3-phosphocholine (SDPC) lipid bilayer gave results in good agreement with experimental data, suggesting an unusually high degree of conformational flexibility of polyunsaturated hydrocarbon chains in membranes. The complete force field is included as Supporting Information and is available from Feller SE, Gawrisch K, MacKerell AD Jr. Polyunsaturated fatty acids in lipid bilayers: intrinsic and environmental contributions to their unique physical properties. J Am Chem Soc 2002 Jan 16;124(2):318-26. More