Solid-state NMR spectroscopy method for determination of the backbone torsion angle ψ in peptides with isolated uniformly labeled residues

We demonstrate a solid-state nuclear magnetic resonance technique, with the acronym ROCSA-LG, for the determination of backbone torsion angles ψ in peptides with multiple, but isolated, uniformly labeled residues. The method correlates the 13C′ chemical shift anisotropy and the 13Cα-1Hα heteronuclear dipolar tensors within a single uniformly labeled residue in a two-dimensional (2D) experiment. The technique requires the measurement of only five 2D spectra and is compatible with high-speed magic-angle spinning. Experimental results are presented for the 17-residue α-helical peptide MB(i+4)EK and for amyloid fibrils formed by the 15-residue peptide Aβ11-25.