Fig. 3. Concentration-dependent helix formation of N_LRS.

Shown are CD spectra in units of MRE values θ_MRE, which directly reflect molecular peptide helicity. (A) Dependence of ellipticity on N_LRS concentrations. The inset shows the best fit of θ(222 nm), jointly with the s_w isotherm of Fig. 2A, with the GMMA model indicated. The GMMA monomer-trimer model results in best-fit helicities of −4290 and −16,210 deg cm² dmol⁻¹ for the monomer (red circle) and trimer (red triangle) state, respectively, corresponding to ≈3 helical residues in the N_LRS monomer increasing to ≈16 helical N_LRS residues per peptide in the trimer. (B) Solvent-induced change in helicity of 0.4 mM N_LRS at different concentrations of TFE. The inset shows θ(222 nm) (circles) and the best-fit two-state model (line) resulting in the best-fit ellipticity of the maximally helical state of −14,400 deg cm² dmol⁻¹ (red open triangle), corresponding to estimated ≈14 helical N_LRS residues per peptide chain.