In Silico, Molecular Docking and In Vitro angiotensin-converting enzyme-inhibitory activity of PGYALQR peptide derived from fish waste hydrolysate

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In recent decades, Angiotensin-converting enzyme (ACE) inhibitory peptides derived from various proteins have become crucial sources of health-enhancing components for clinical use. Abundant proteins in fish waste entrails can be used to produce ACE inhibitory peptides. Catfish, Tilapia, and Mackerel entrails were digested by pepsin and passed through the 3kDa cutoff column. The protein hydrolysate passed through the 3kDa cutoff column and C18 column were analyzed for an ACE inhibitory activities and sequenced using LC-MS/MS. Five candidate peptides from De novo sequencing was chemically synthesized and tested for ACE inhibitory activity. The ACE inhibitory activity result revealed that PGYALQR peptide contains ACE inhibitory activity as captopril did. This study aims to predict the conformation and orientation of the PGYALQR peptide into the binding site of ACE. Molecular docking analysis using AutoDock Vina was performed to elucidate the mechanisms underlying the ACE-inhibitory activity of the PGYALQR peptide. Computational analysis revealed that the peptide binds to the ACE active site with −11.2 kcal/mol, forming hydrogen bonds with Glu162, Gln281, His353, Ala354, Lys511, His513, and Tyr523. In comparision, captopril interacted with Gln281, His353, Lys511, His513, Tyr520, and Tyr523 with a binding energy of −5.9 kcal/mol. Additionally, the peptide interacts with the Zn (II) ion in the ACE active site, coordinating with the residues Glu411, His383, and His387, which is crucial for enhancing its inhibitory activity of ACE. It may contort the tetrahedral coordination of the Zn (II), resulting in loss of ACE activity.