Free energy changes in lysozyme denaturation.

Previous work has shown that native lysozyme (N) is completely denatured by the addition of guanidinium chloride (conformation D) but that partially denatured conformations appear in other denaturants. Conformation I appears when LiClO4 is added to the protein, and conformation II is caused by heating. We have now determined the apparent free energy changes for the reversible processes between N and the three unfolded conformations and for the process between II and D. This allows us to estimate the apparent free energy changes for a process between any two of these four conformations.