Simulation of the thermal denaturation of hen egg white lysozyme: trapping the molten globule state.

In the study of protein folding, much attention has focused on the characterization of folding intermediates. We report here molecular dynamics simulations in which the initial stages of the thermal denaturation of hen egg white lysozyme in aqueous solution are examined in detail. It is found that lysozyme unfolds in a two-stage process with the initial formation a quasi-stable state in which significant rearrangement of the secondary structure takes place. No evidence for distinct folding domains was found. The simulations suggest that the formation of well-defined secondary structure occurs after the initial collapse of the peptide chain and thus tend against the framework model of protein folding.