Identification and target of action of cholecystokinin-releasing peptides from simulated digestion hydrolysate of wheat protein

BACKGROUND Wheat protein intake leads to improved appetite control. However, the active components causing appetite in wheat have not been fully clarified. Gut cholecystokinin (CCK) plays a vital role in appetite control. This study aimed to investigate the ability of wheat protein digest (WPD) to stimulate CCK secretion and clarify the active components and target of action. RESULTS WPD was prepared by a simulated gastrointestinal digestion model. WPD treatment with a concentration of 5 mg mL −1 significantly stimulated CCK secretion in enteroendocrine STC-1 cells ( P < 0.05). Furthermore, oral gavage with WPD in mice significantly increased plasma CCK level at 60 min ( P < 0.01). Preparative C18 column separation was used to isolate peptide fractions associated with CCK secretion and peptide sequences were identified by liquid chromatography–tandem mass spectrometry. A new CCK-releasing peptide, RYIVPL, that potently stimulated CCK secretion was successfully identified. After pretreatment with a specific calcium-sensing receptor (CaSR) antagonist, NPS 2143, CCK secretion induced by WPD or RYIVPL was greatly suppressed, suggesting that CaSR was involved in WPD- or RYIVPL-induced CCK secretion. CONCLUSION The present study demonstrated that WPD has an ability to stimulate CCK secretion in vitro and in vivo , and determined that peptide RYIVPL in WPD could stimulate CCK secretion through CaSR. © 2023 Society of Chemical Industry.