A criterion that determines fast folding of proteins: A model study

Abstract

We consider the statistical mechanics of a full set of two-dimensional protein-like heteropoly- mers, whose thermodynamics is characterized by the coil-to-globular (T�) and the folding (Tf) transition temperatures. For our model, the typical time scale for reaching the unique native con- formation is shown to scale asf ∼ F(M)exp(�/�0), where � = 1 − Tf/T�, M is the number of residues, and F(M) scales algebraically with M. We argue that Tf scales linearly with the inverse of entropy of low energy non-native states, whereas Tis almost independent of it. As � → 0, non-productive intermediates decrease, and the initial rapid collapse of the protein leads to struc- tures resembling the native state. Based solely on accessible information, � can be used to predict sequences that fold rapidly.