Absence of reptation in the high-temperature folding of the trpzip2 $β$-hairpin peptide Available to Purchase

We have carried out extensive all atom explicit solvent simulations of the high-temperature folding and unfolding of the trpzip2 $β$-hairpin peptide and examined the resulting trajectories for evidence of folding via a reptation mechanism. Over 300 microcanonical simulations of 10 ns each were initiated from a Boltzmann ensemble of conformations at $425K$⁠. Though we observed numerous folding and unfolding events, no evidence of reptation was found. The diffusional dynamics of the peptide are orders of magnitude faster than any observed reptation-like motion. Our data suggest that the dominant mechanisms for $β$-hairpin folding under these conditions are hydrophobic collapse and turn formation, and that rearrangements occur via significant expansion of the polypeptide chain.