In silico investigation of action mechanism of four novel angiotensin-I converting enzyme inhibitory peptides modified with Trp

To potentiate activities of angiotensin-I converting enzyme (ACE) inhibitory peptides VK, YA, KY and TAY from oyster hydrolysate, four novel tripeptides VKW, YAW, KYW and TAW were designed by modification with Trp at the C-terminus. The tripeptides were synthesized, and their 50% ACE inhibitory concentrations (IC50) were measured to be 0.020, 0.49, 0.43 and 0.63 µM, respectively. Their activities increased 27-1450 times compared to their corresponding original peptides. All peptides did not show toxicity on the Chang cell. Molecular docking and molecular dynamics simulation showed that modification with Trp can enhance the stability of ACE/derived peptide complexes by increasing binding affinity and interaction sites with important amino acid residues. Interactions between peptides with amino acid residues of ACE GLN281, ALA354, GLU411, PHE457 and LYS511 played an important role in activity improvement of derived peptides. Modification with Trp at the C-terminus was an effective way for designing novel ACE inhibitory peptides.