High-resolution J-coupled 13C MAS NMR spectroscopy of lipid membranes

We propose the use of Lee–Goldburg decoupling in high-resolution natural abundance 13C CP-MAS NMR spectroscopy to obtain J-resolved multiplets from membrane lipids, and the use of these in spectral assignment and to investigate changes in molecular and segmental dynamics within chemical shift-resolved lipid groups. Spectroscopic characteristics of hydrated DPPC bilayers are reported, including J1CH-couplings from the liquid crystalline and gel phases. The observed J1θCH values are scaled in the Lee–Goldburg experiment by a factor of approximately 3−1/2 and corrected J1CH values on the order of 150 Hz compare well with indirect measurements. The J-resolved multiplets show J1θCH-couplings from the chain region to be approximately 20% lower than couplings determined from the headgroup, with backbone values falling between the two. Sensitivity of Lee–Goldburg decoupling to molecular motions reveals changes in hydrocarbon chain and backbone segmental dynamics across the main phospholipid transition and reduction in headgroup mobility below the pre-transition.