Fig. 5. Proposed mechanism of temperature-induced unfolding and transitioning from reversible to irreversible lysozyme fibrils.

The sub-domain B (purple) of the native fold is the first region to denature upon heating and can form the core of the reversible fibrils upon cooling. Longer heating time leads to a full denaturation of the protein, allowing the sub-domain A residues (green) to adopt the beta structure required for the formation of the irreversible fibrils.