Exposure of thiol groups in the heat-​induced denaturation of β-​lactoglobulin

Protein aggregates can be stabilized by disulfide bridges. The whey protein β-​lactoglobulin (β-​lac) contains a disulfide bridge and a free cysteine that are shielded from the solvent by an α-​helix. These groups are important in the thiol-​disulfide exchange that occurs during aggregation and gelation of β-​lac. Replica exchange mol. dynamics simulations show that the exposure mechanism is very different for the 2 buried groups. While melting of the α-​helix enhances exposure of the free cysteine, it does not for the buried bridge. These findings shed light on the mol. mechanism of the first step of β-​lac denaturation and aggregation.