Figure 2.

Results from kinetic characterization of Pin (a, c, and e) and FBP (b, d, and f) folding. (a and b) The ensemble fraction of native contacts is shown as a function of time, along with the best-fit single exponential in red [〈Q(t)〉 is scaled by the fitting parameter A₀]. (c and d) The residual to this single exponential. (e and f) The residual to the best-fit double exponential. Pin WW domain is found to fit to a single exponential (Eq. 1) with parameters A₀ = 0.39, A₁ = 0.23, and k₁ = 5.5 × 10⁻⁵ τ⁻¹, whereas FBP WW domain is found to fit to a double exponential (Eq. 2) with parameters A₀ = 0.64, A₁ = 0.37, k₁ = 3.9 × 10⁻⁵ τ⁻¹, A₂ = 0.10, and k₂ = 5.8 × 10⁻⁶ τ⁻¹, where τ is the fundamental time scale (see Methods).