Practice question

Folded helical peptide displays characteristic NOESY pattern with dominant sequential amide-amide connectivities Ni to Ni+1 along backbone, reflecting regular short NH-NH distances in helical geometry. Additionally, medium-range NOEs like alpha to amide i to i+3 and alpha to beta i to i+3 appear, while long-range NOEs are sparse. Observing strong Ni-Ni+1 ladder with these medium contacts, combined with small coupling constants and upfield C-alpha chemical shift index, indicates stable helix. Such pattern is absent in random coil, confirming ordered helical conformation in aqueous solution.