Oxidation Changes Physical Properties of Phospholipid Bilayers: Fluorescence Spectroscopy and Molecular Simulations

Physical properties of oxidized phospholipid (OxPL) membranes consisting of binary mixtures of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 10 mol% of one of two OxPLs, 1-palmitoyl-2-glutaryl-sn-glycero-3-phosphocholine (PGPC) or 1-palmitoyl-2-(5'-oxo-valeroyl)-sn-glycero-3-phosphocholine (POVPC), were investigated experimentally and computationally. Fluorescence solvent relaxation (SR) and fluorescence correlation spectroscopy z-scan (FCS z-scan) show increased headgroup hydration and mobility, and faster lateral diffusion in POPC membrane upon addition of OxPLs. The magnitudes of both effects arc distinct for each of the two OxPLs. Molecular dynamics simulations corroborate the experimental findings, providing at the same time a detailed molecular interpretation in terms of changes in bilayer structure and phospholipid orientation.