  We consider a simplified model of protein folding, with binary degrees of
freedom, whose equilibrium thermodynamics is exactly solvable. Based on this
exact solution, the kinetics is studied in the framework of a local equilibrium
approach, for which we prove that (i) the free energy decreases with time, (ii)
the exact equilibrium is recovered in the infinite time limit, and (iii) the
folding rate is an upper bound of the exact one. The kinetics is compared to
the exact one for a small peptide and to Monte Carlo simulations for a longer
protein, then rates are studied for a real protein and a model structure.
