ON THE THERMODYNAMIC HYPOTHESIS OF PROTEIN-FOLDING

The validity of the thermodynamic hypothesis of protein folding was ex plored by simulating the evolution of protein sequences. Simple models of lattice proteins were allowed to evolve by random point mutations subject to the constraint that they fold into a predetermined native s tructure with a Monte Carlo folding algorithm. We employed a simple an alytical approach to compute the probability of violation of the therm odynamic hypothesis as a function of the size of the protein, the frac tion of the total number of possible conformations which are kinetical ly accessible, and the roughness of the free-energy landscape. It was found that even if the folding is under kinetic control, the sequence will evolve so that the native state is most often the state of minimu m free energy.