Umami-enhancing effect of typical kokumi-active γ-glutamyl peptides evaluated via sensory analysis and molecular modeling approaches

The umami-enhancing effect of typical kokumi-active gamma-glutamyl peptides was verified by sensory evaluation. To investigate the umami-enhancing molecular mechanism of the peptide on monosodium glutamate (MSG) taste, a novel hypothetical receptor, taste type 1 receptor 3 (T1R3)-MSG complex, was constructed. These peptides demonstrated strong interactions with T1R3-MSG. Moreover, four amino acid residues, Glu-301, Ala-302, Thr-305, and Ser-306, were critical in ligand-receptor interactions. In detail, gamma-Glu-gamma-Glu-Val (gamma-E-gamma-EV) readily interacts with T1R3 through hydrogen bonds and hydrophobic interactions. While gamma-E-gamma-EV did not bind to MSG, gamma-Glu-Val (gamma-EV) and gamma-Glu-Leu (gamma-EL) showed high binding affinity to MSG and interacted with T1R3 through hydrophobic bonds suggesting that the interactions between dipeptides and T1R3-MSG were weaker than tripeptides. These results demonstrated that kokumi-active gamma-glutamyl peptides could enhance the umami taste of MSG, and exhibit synergistic effects in activating T1R3. This study provides a theoretical reference for interactions between the novel umami-enhancing substances and umami receptor.