The solution structure and stability of the different sequences used in this study were confirmed by CD melting and NMR spectroscopies as described previously. CD experiments were performed on solutions prepared following the same protocol as for ESI-IM-MS. CD spectra were recorded on spectrophotometer Jasco J-1500 at 20°C. The measured CD ellipticity (θ, in milidegrees) was transformed to molar circular dichroic absorption (Δε) using Equation ( ):