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 J¹_CH-couplings from the liquid crystalline and gel phases. The observed J^1θ_CH values are scaled in the Lee-Goldburg experiment by a factor of approximately 3^-1/2 and corrected J¹_CH values on the order of 150 Hz compare well with indirect measurements. The J-resolved multiplets show J^1θ_CH-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.