We present a new method that combines carbonyl-selective labeling with frequency-selective heteronuclear recoupling to resolve the spectral overlap of magic angle spinning (MAS) NMR spectra of membrane proteins in fluid lipid membranes with broad lines and high redundancy in the primary sequence. We implemented this approach in both heteronuclear 15N- 13Cα and homonuclear 13C-13C dipolar assisted rotational resonance (DARR) correlation experiments. We demonstrate its efficacy for the membrane protein phospholamban reconstituted in fluid PC/PE/PA lipid bilayers. The main advantage of this method is to discriminate overlapped 13Cα resonances by strategically labeling the preceding residue. This method is highly complementary to 13Ci-1′-15Ni- 13Ciα and 13Ci-1α-15N i-1-13Ci′ experiments to distinguish inter-residue spin systems at a minimal cost to signal-to-noise.
- Frequency-selective dipolar recoupling
- Heteronuclear recoupling
- Magic angle spinning
- Membrane proteins
- Solid-state NMR