Mechanism of bile salt-promoted β-lactoglobulin digestion: a structural demasking perspective

CD/FTIR showed limited secondary-structure rearrangement after BS exposure. • ANS fluorescence indicated increased hydrophobic exposure after BS addition. • Bile salts increase the accessibility of cleavage sites near hydrophobic cores. • LC–MS revealed BS-dependent changes in β-Lg peptide profiles. • Bile salts reroute proteolysis via site-specific demasking. The structural stability of the β-lactoglobulin (β-Lg) lyx confers high resistance to gastric proteolysis. While bile salts are known to promote its intestinal digestion, the specific conformational mechanisms and their impact on the resulting peptide cleavage patterns are not fully understood. In this study, we investigated the influence of bovine bile salts on the structural reorganization and digestibility of β-Lg during simulated gastrointestinal digestion. Conformational analyses indicated that bile salts induced limited structural perturbation within an overall retained secondary-structure framework, accompanied by increased exposure of hydrophobic regions. These changes were consistent with increased accessibility of selected cleavage regions. LC–MS peptide mapping showed that bile salts altered the peptide profile and promoted the degradation of regions that were more resistant under BS-free conditions. Overall, the findings support a demasking-related interpretation of how bile salt–protein interactions may influence β-Lg proteolysis under simplified in vitro conditions. Download: Download high-res image (544KB) Download: Download full-size image