Fig. 3.

Coil-to-helix transition induced by protonation of side-chain 1,2,3-triazole. a The pH titration curve of P1 with side-chain triazoles and P2 without side-chain triazoles. b CD spectra of P1 upon stepwise addition of concentrated HCl. c The mean residue molar ellipticity of P1 at 222 nm (−[θ]_222 nm) after alternating addition of HCl and NaOH over five cycles. At pH ~ 2.8 (light grey background), P1 adopts an α-helical conformation with a positive −[θ]_222 nm value; at pH ~ 9.5 (white background), the value of −[θ]_222 nm is approximately zero indicating a random coil structure