Synergistic umami-enhancing mechanism of novel umami peptides from Mactra Veneriformis and Ruditapes Philippinarum clams with four basic umami substances by multi-ligand molecular docking, molecular dynamics simulations and stably transfected umami receptor cells.

Current research is predominantly centered on the rapid screening of novel umami peptides and their interactions with individual flavor enhancer, while limited attention has been paid to the synergistic umami-enhancing effects between umami peptides and different types of umami enhancers. This study aims to investigate the synergistic effects and taste mechanism of 16 novel umami peptides from Mactra Veneriformis and Ruditapes Philippinarum clams in combination with four umami substances-MSG, IMP, GMP, and WSA. Electronic tongue and sensory evaluation analyses revealed that 16 umami peptides exhibited synergistic umami-enhancing effects with MSG, GMP, and WSA, whereas 14 umami peptides (except for TGFLPEEYMK and KALSEELDN) demonstrated synergy with IMP. Notably, markedly enhanced umami perception was observed for the combinations of AMKLEKENAL and MSG, AAEAKLELLE and IMP, DDLDR and GMP, as well as DEELNKLL and WSA, with corresponding umami enhancement rates of 83.75%, 95.00%, 80.00%, and 82.50%, respectively. Multi-ligand molecular docking indicated that the 16 umami peptides cooperatively bound to the receptor T1R1/T1R3 together with the four umami enhancers via new key residues. Molecular dynamics simulations involving multiple ligands showed that the four peptides stably integrated into T1R1/T1R3 in their respective ternary systems through electrostatic and hydrogen-bonding interactions, thereby elevating umami perception. The synergistic umami-enhancing effects of four umami peptide-umami agent combinations were verified by changes in Ca2+ concentration in T1R1/T1R3-HEK-293 T cell. This study provides valuable theoretical guidance for understanding the umami mechanism in complex system and highlights the potential of clam-derived umami peptides as natural flavor enhancers in food industry.