The free energy barrier
As has been emphasized the free energy barrier arises from
the significant reduction in entropy required to achieve the
folded state. The Kramer’s rate law gives the folding time
for crossing over the barrier to the folded state taking the
diffusive hopping among many states into account. The
transition free energy is:
Socci, Onuchic, Wolynes J. Chem. Phys. 1996, 104 5860-5868