Spectral editing of alanine, serine, and threonine in uniformly labeled proteins based on frequency-selective homonuclear recoupling in solid-state NMR

Spectral editing is crucial to simplify the crowded solid-state NMR spectra of proteins. New techniques are introduced to edit C-13-C-13 correlations of uniformly labeled proteins under moderate magic-angle spinning (MAS), based on our recent frequency-selective homonuclear recoupling sequences [Zhang et al., J. Phys. Chem. Lett. 2020, 11, 8077-8083]. The signals of alanine, serine, or threonine residues are selected out by selective C-13 alpha-C-13 beta double-quantum filtering (DQF). The C-13 alpha-C-13 beta correlations of alanine residues are selectively established with efficiency up to similar to 1.8 times that by dipolar-assisted rotational resonance (DARR). The techniques are shown in 2D/3D NCCX experiments and applied to the uniformly C-13, N-15 labeled Aquaporin Z (AqpZ) membrane protein, demonstrating their potential to simplify spectral analyses in biological solid-state NMR.

Automated summary

Spectral editing is essential for simplifying crowded solid-state NMR spectra of proteins. New techniques utilizing selective C-13 alpha-C-13 beta double-quantum filtering show promise in efficiently selecting signals of specific amino acid residues. These methods have the potential to streamline spectral analyses in biological solid-state NMR.