Fig. 7. CD thermal denaturation profiles demonstrate that Fra1W interacts with Fra1 but not cJun. Shown are thermal stability of peptide pairs measured via temperature dependence of the CD signal at 222 nm. (a) The thermal denaturation profile cJun–Fra1W indicates no difference from the average of the component peptides (black line vs. red hash) indicating no interaction. (b) Fra1–Fra1W shows a substantial increase in the transition midpoint (T_m = 64 °C) relative to component peptides (black vs. red hash). All experiments were performed in 10 mM potassium phosphate and 100 mM potassium fluoride (pH 7.0). All spectra were recorded at 1 °C increments at a total peptide concentration of 150 μM and fitted to a two-state denaturation model.