(A) Circular dichroism (CD) spectra of Ser546 (dashed blue line) and pSer546 (solid red line) peptides in neutral pH phosphate buffer at 0°C, indicating their triple-helical conformation, and at 70°C (Ser546, dotted blue line; pSer546, dashed red line), showing their unfolded state. CD temperature scans of Ser546 (dashed blue line) and pSer546 (solid red line) at (B) neutral pH and (C) pH 2.9 are shown. (D) Refolding profiles of Ser546 (dotted blue line) and pSer546 (solid red line) at 0°C (pH 7.4). Data are representative of three independent experiments and depict mean ± SEM. To see this figure in color, go online.