Separation and enrichment of multiple bile acid micelle-disrupting peptides by adsorption/desorption process with heat-treated porous silica gels

Abstract

Bile acid (BA) micelle-disrupting peptides are bioactive peptides (BPs) that suppress intestinal cholesterol adsorption and ameliorate blood cholesterol levels. To facilitate their application in the food industry, an effective and straightforward technology for BP separation and enrichment of BPs is required. For this purpose, we assessed the potential of heat-treated (HT) porous silica gels with an enhanced capacity for peptide adsorption/desorption (AD). Given the key characteristics of these peptides involving basic amino acid (AA) residues, we applied casein hydrolysate to HT silica gels for adsorption at neutral pH, where the surface yielded anionic silanolates through deprotonation. Subsequently, desorption was conducted at pH 2, at which point the surface returned to its neutral state. We confirmed a 335-fold increase in the BA micelle-disrupting activity of the resulting hydrolysates. LC-MS/MS analysis identified 783 peptides, confirming that the peptides containing cationic AA residues were selectively enriched, as expected. Moreover, a dose-response of randomly selected 27 peptides with various enrichment levels revealed the presence of multiple active peptides in the enriched groups. These results indicate that our method is effective for the separation and enrichment of BA micelle-disrupting peptides and holds promise for BP production.