FIGURE 2.

The figure illustrates the energy path along the folded ⇆ unfolded reaction path. is the activation energy for the process f → u when F = 0. With finite tension, the net activation energy is reduced so that where Δx_f→u is the activation length, akin to an activation volume for solid-state reactions. The activation length for the refolding transition is Δx_u→f; note Δx_u→f < 0. When F = F_at, ΔG = 0 and there is an athermal driving of all domains into the unfolded state.