NMR Characterization of SARS-CoV-2 SR-Peptide and Interactions

One-dimensional (1D) ¹H NMR experiments and two-dimensional (2D) ¹H-¹H TOCSY, NOESY, and ¹H-¹⁵N/¹H-¹³C heteronuclear single quantum coherence (HSQC) experiments of the SR-peptide (residues A182-S197) of N^SARS-CoV-2 were acquired at 5 °C on a Bruker 700 MHz spectrometer equipped with a triple-resonance 5 mm cryogenic probe using the software Top Spin 3.5 (Bruker). The peptide concentration was 4 mM for resonance assignment and 200 µM for the interaction analysis with polyU (800 kDa). Samples were in 50 mM NaP, 0.01% NaN₃ and 5% D₂O. Spectra were processed with TopSpin 3.6 (Bruker) and analyzed using Sparky^{35 (link)}. Secondary structure was analyzed subjecting experimental HA, HN, N, CA and CB chemical shifts to TALOS+^{36 (link)}. The chemical shift perturbation (CSP) for the peptide residues is the one of the NH protons from the TOCSY experiment. The CSP error is based on the resolution of the spectra.