Fig. 1.

The dipeptide GM induces peptide exchange on A2. (Left) A2–NLVPMVATA monomers were incubated with or without 10 mM of the dipeptide GM, and the association rate of added NLVPK_FITCVATV was measured using fluorescence anisotropy. Association rate constants (k_on ± SEM) are 0.15 ± 0.02 × 10³ M⁻¹⋅s⁻¹ without GM and 3.93 ± 0.86 × 10³ M⁻¹⋅s⁻¹ with GM. Another exchange reaction is shown in Fig. S1D. (Center) An analogous experiment the measuring dissociation rate of NLVPK_TAMRAVATA peptide in the presence or absence of GM, with 10 µM NLVPMVATV peptide. The dissociation rate constant (k_off ± SEM) is 2.16 ± 0.03 × 10⁻⁶⋅min⁻¹ with GM. (Right) Exchange of A2-bound NLVPMVATA peptide for NLVPMVATV. A2–NLVPMVATA was incubated for 180 min with 10 µM NLVPMVATV peptide in the presence or absence of 10 mM GM. Thermal stability of the resulting A2–peptide complexes was measured by TDTF; the minimum of the each curve indicates the melting temperature (T_m) of the complex. The TDTF curves of A2 folded with the respective peptides are shown in Fig. S1 A and B.