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

Abstract

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 J1thetaCH 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 J1thetaCH-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.