Figure 4.

Ion-specific effect on the CD spectra and donor-acceptor fluorophore separation R_DA of (AK)₁₄. (A) Measured R_DA (symbols) in the absence of salt at pH 7 (black), with KCl (yellow upper triangles), GdmCl (red squares), NaClO₄ (green circles), and no salt pH 11 (light blue line). Standard deviations from several measurements are smaller than the size of the symbol (0.05 nm). Estimated range of R_DA from MD-derived structures at 3.5M salt is represented as shaded areas depicting the upper and lower limits. (B) The salt-dependent helicity (derived from the signal at 222 nm) of (AK)₁₄ in the absence of salt at pH 7 (black), with KCl (yellow), GdmCl (red), NaClO₄ (green), and no salt pH 11 (light blue). The average value is a dotted line while the thickness of the shaded area represents the upper and lower boundaries. (C) CD spectra of (AK)₁₄ in the absence of salt at pH 7 (black), with KCl (yellow), GdmCl (red), NaClO₄ (green), and no salt pH 11 (light blue).