Minimum model for the α‐helix–β‐hairpin transition in proteins

We present a minimal model for proteins, which is able to capture the structural conversion between the α‐helix and β‐hairpin. In most regimes of the parameter space, the model produces a stable structure at a low temperature; in a few limited regimes of the parameter space, the model displays an β‐hairpin transition as the physical conditions vary. These variations include a perturbation on hydrogen bonding propensity at the middle of the modeled chain, or the change of the hydrophobicity of a designated pair along the chain. Using Monte Carlo simulations, we demonstrate the structural conversion by means of state diagrams, heat capacity maps, and free energy maps. Proteins 2007. © 2007 Wiley‐Liss, Inc.