Canonical and micro-canonical analysis of folding of trpzip2: An all-atom replica exchange Monte Carlo simulation study

The density of states of trpzip2, a β-hairpin peptide, has been explored at all-atom level. Replica exchange Monte Carlo method was used for sufficient sampling over a wide range of temperature. Micro-canonical analysis was performed to confirm that the phase transition behavior of this two-state folder is first-order-like. Canonical analysis of heat capacity suggests that hydrogen bonding interaction exerts a considerable positive influence on folding cooperativity, in contrast, hydrophobic interaction is insufficient for high degree of folding cooperativity. Furthermore, we explain physical nature of the folding process from free energy landscape perspective and extensively analyse hydrogen bonding and stacking energy.