McKenzie Iain, DiPasquale Mitchell, Dziura Maksymilian, Gutberlet Thomas, Hartwig Nathan A, Karner Victoria L, Scheuermann Robert, Marquardt Drew
Centre for Molecular and Materials Science, TRIUMF, 4004 Wesbrook Mall, Vancouver, V6T 2A3, BC, Canada; Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, V5A 1S6, BC, Canada; Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, N2L 3G1, ON, Canada.
Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, N9B 3P4, ON, Canada.
Chem Phys Lipids. 2025 Aug;270:105496. doi: 10.1016/j.chemphyslip.2025.105496. Epub 2025 May 30.
The physical properties of lipid bilayers are known to depend on their composition, but there has recently been controversy about whether cholesterol (chol) does or does not stiffen biomembranes containing unsaturated phospholipids. Herein, avoided level crossing muon spin resonance (ALC-μSR) spectroscopy has been used to probe the local dynamics in model biomembranes composed of the saturated phospholipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), the unsaturated phospholipids 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), and the sterol chol. The presence of chol significantly stiffens the acyl chains in lipid mixtures as evident from the reduction of the amplitude of restricted reorientational motion in the acyl chain at the C-C position and the increase of the torsional barrier for rotation about the bonds in the acyl chain. Swapping POPC for DOPC slightly increases the amplitude of restricted reorientational motion and decreases the torsional barrier of the acyl chains, but the magnitude of the effect is much smaller than the inclusion of chol.
