Site-specific ϕ- and ψ-torsion angle determination in a uniformly/extensively 13C- and 15N-labeled peptide

► Determination of ϕ- and ψ-torsion angles of a uniformly 13C-/15N-labeled peptide. ► Rotational-echo double resonance (REDOR) NMR. ► Tri-spin systems, 15N(i)-1Hα(i)-15N(i + 1) and 13C′(i − 1)-1HN(i)-13C′(i).