FIGURE 5.

Ligand-binding induced folding experiment. A, experimental traces at 0, 5, and 40 μm peptide (LQRRRETQV). The initial “burst phase” is the previously characterized binding of peptide to the native state (26). B, observed rate constants for the ligand-induced folding phase decreased as a function of peptide concentration consistent with a slow folding step followed by a rapid bimolecular association (6, 36). C, the amplitudes for the ligand-induced folding phase switch from negative to positive, which is consistent with the proposed mechanism if the fluorescence of the intermediate is at least 10% higher than that of the native state.