Lateral Diffusion of Phospholipids Measured using 31P Centreband-only Detection of Exchange Nuclear Magnetic Resonance

Lateral diffusion of phospholipids is a process essential to membrane function, and can be measured by nuclear magnetic resonance (NMR). This project will use CODEX (Centerband-Only Detection of Exchange), the most highly-evolved NMR experiment combining magic angle spinning with exchange sensitivity, to measure lateral diffusion. 31P CODEX NMR measurements were performed on phospholipids in small unilamellar vesicles (SUV) in a high viscosity solution to slow the rotational tumbling of the SUV and minimize its influence on the CODEX decay. For SUV composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), alone or mixed with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) or cholesterol (CHOL), 31P CODEX spectra showed well-resolved resonances for POPC and POPG, with monoexponential decays for both, from which the correlation time for molecular motion could be extracted. The lateral diffusion coefficients were determined, and fell in the range of 1.0 - 3.3 x 10-12 m2s-1 at 10°C, which agree with established literature values for POPC and POPG.MAS