Structure and Dynamics of Cholesterol-Containing Polyunsaturated Lipid Membranes Studied by Neutron Diffraction and NMR

A direct and quantitative analysis of the internal structure and dynamics of a polyunsaturated lipid bilayer composed of 1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine (18:0-22:6n3-PC) containing 29 mol% cholesterol was carried out by neutron diffraction, 2H-NMR and 13C-MAS NMR. Scattering length distribution functions of cholesterol segments as well as of the sn-1 and sn-2 hydrocarbon chains of 18:0-22:6n3-PC were obtained by conducting experiments with specifically deuterated cholesterol and lipids. Cholesterol orients parallel to the phospholipids, with the A-ring near the lipid glycerol and the terminal methyl groups 3 Å away from the bilayer center. Previously, we reported that the density of polyunsaturated docosahexaenoic acid (DHA, 22:6n3) chains was higher near the lipid–water interface. Addition of cholesterol partially redistributes DHA density from near the lipid–water interface to the center of the hydrocarbon region. Cholesterol raises chain-order parameters of both stearic acid and DHA chains. The fractional order increase for stearic acid methylene carbons C8–C18 is larger, reflecting the redistribution of DHA chain density toward the bilayer center. The correlation times of DHA chain isomerization are short and mostly unperturbed by the presence of cholesterol. The uneven distribution of saturated and polyunsaturated chain densities and the cholesterol-induced balancing of chain distributions may have important implications for the function and integrity of membrane receptors, such as rhodopsin

High resolution 2D correlation of cholesterol in model membrane

International audienc

15NT2′ relaxation times of bacteriorhodopsin transmembrane amide nitrogens

International audienc

Understanding Sterol-Membrane Interactions, Part II: Complete 1 H and 13 C Assignments by Solid-State NMR Spectroscopy and Determination of the Hydrogen-Bonding Partners of Cholesterol in a Lipid Bilayer

International audienc

Understanding Sterol-Membrane Interactions Part I: Hartree-Fock versus DFT Calculations of 13 C and 1 H NMR Isotropic Chemical Shifts of Sterols in Solution and Analysis of Hydrogen-Bonding Effects

International audienc

High-resolution 13C NMR of sterols in model membrane

International audienc