Effects and mechanisms of a novel peptide LADW on angiotensin I-converting enzyme and vascular function and its gastrointestinal stability: an in vitro and in silico study

The novel peptide LADW has umami taste characteristic, while its health benefits and gastrointestinal stability have not been investigated. This study used in vitro and in silico experiments to investigate the effects and mechanisms of this peptide on angiotensin I-converting enzyme (ACE1) and vascular function, and its gastrointestinal stability was also evaluated by a simulated digestion. Results demonstrated that LADW exhibited a good inhibitory effect against ACE1, with an IC 50 value of 28.02 ± 1.52 μM. Kinetics, isothermal titration calorimetry, and thermal shift assay revealed that LADW competitively binds ACE1, with multi-site, entropy-driven interactions and slight conformational modulation. Molecular docking and molecular dynamics simulations showed that the LADW effectively bound to the active site of ACE1 mainly through hydrogen bonding and hydrophobic interactions, stabilized the conformation of ACE1, and reduced the fluctuation of the most active amino acid residues, such as Glu411, Ala354 and Glu384. Meanwhile, the LADW promoted the nitric oxide (NO) release and inhibited the endothelin-1 (ET-1) secretion. Further analysis showed that the LADW formed strong interactions with several key proteins in the regulation of NO and ET-1 release, namely endothelial nitric oxide synthase, endothelin-converting enzyme-1 and Furin. In addition, the LADW showed a good gastrointestinal stability after a simulated gastrointestinal digestion in vitro with a retention rate of 48.37 ± 3.00 %. The findings of this study may contribute to the elucidation of the potential benefits of the peptide LADW in reducing blood pressure and safeguarding the cardiovascular system, thereby offering a foundation for further research.