Figure 3.

CD spectra of Ac-SKAAAAKAAAAKAAGY-NH₂ peptides with serine modifications [unmodified Ser (free hydroxyl), SerOGlcNAc, SerOPO₃H^– (pH 4), and SerOPO₃^2– (pH 8)] (left) and with Ser replaced with Ala (right): unmodified Ser (green squares), dianionic phosphoserine (pH 8) (red circles), monoanionic phosphoserine (pH 4) (open magenta circles), SerOGlcNAc (blue diamonds), and Ala (black triangles). CD experiments were conducted in water with 10 mM phosphate (pH 7 or as indicated) and 25 mM KF at 0.5 °C. Data are the average of at least three independent trials. Data were background corrected but were not smoothed. Individual CD spectra of all peptides, with error bars shown, are given in the Supporting Information.