FIGURE 7.

(A) The equilibrium distribution of the end-to-end distance at extremely high temperature (T = 1500 K). Even at this elevated temperature, the fully stretched conformations of R = 13.5 nm (arrow) are not found in the ensemble of thermally denatured conformations. (B) Refolding is initiated by a force-quench from the initial value f_S = 90 pN to f_Q = 4 pN. The five time-traces show great variations in the relaxation to the hairpin conformation. However, in all trajectories, R decreases in at least three distinct stages that are explicitly labeled for the trajectory in green.