A pulse sequence that yields three-dimensional
1H chemical shift /
1H-
15N heteronuclear dipolar coupling /
15N chemical shift solid-state NMR spectra is demonstrated on a uniformly
15N labeled membrane protein in magnetically aligned phospholipid bilayers. Based on SAMPI4, the pulse sequence yields high
resolution in all three dimensions at a
1H resonance frequency of 900 MHz with the relatively low rf field strength (33 kHz) available for a lossy aqueous sample with
a commercial spectrometer and probe. The
1H chemical shift frequency dimension is shown to select among amide resonances, which will be useful in studies of larger
polytopic membrane proteins where the resonances overlap in two-dimensional spectra. Moreover, the
1H chemical shift, which can be measured from these spectra, provides an additional orientationally dependent frequency as
input for structure calculations.
Keywords Bicelle - Membrane protein - Aligned sample - Protein structure
Both Alexander A. Nevzorov and Sang Ho Park contributed equally to this work.