  Among an infinite number of possible folds, nature has chosen only about 1000
distinct folds to form protein structures. Theoretical studies suggest that
selected folds are intrinsically more designable than others; these selected
folds are unusually stable, a property called the designability principle. In
this paper we use the 2D hydrophobic-polar lattice model to classify structures
according to their designability, and Langevin dynamics to account for their
time evolution. We demonstrate that, among all possible folds, the more
designable ones are easier to unfold due to their large number of surface-core
bonds.
