Entropic barriers, frustration, and order: Basic ingredients in protein folding

We consider the intrinsic entropy and energy barriers of cross-linking in a set of M monomers, plus minimal kinetic restrictions on the folding process of a proteinlike molecule. For a finite-size chain, there is an effective folding transition to an ordered structure. Without frustration, this state is reached in a time that scales as M(lambda). with lambda similar or equal to 3. This scaling is limited by the amount of frustration which leads to the dynamical selectivity of proteins in a well defined range of temperatures, and M less than or similar to 300 monomers. These predictions resemble generic properties of in live globular proteins.