Comprehensive review on some food-derived bioactive peptides with anti-hypertension therapeutic potential for angiotensin-converting enzyme (ACE) inhibition

Angiotensin-converting enzyme (ACE) inhibitory peptides have lately attracted interest since functional foods that help maintain homeostatic regulations have been developed. Rarely discussed are the intrinsic ACE-peptide interactions and their positioning, both of which help illustrate the ACE inhibitory functionalities in food-derived peptides. In this study, 173 ACE inhibitory peptides were collated using the UWM-BIOPEP database. The sequences were grouped into short, medium, and long peptides. The hydrophobicity/hydrophilicity property of peptides was analyzed using Peptide2 and the peptide binding site on ACE was predicted using PepSite2. Peptide residues interacting with ACE were denoted as reactive amino acids. Molecular docking analysis was conducted to simulate ACE-peptide binding and delineate the roles of reactive amino acids at the ultimate, penultimate, and antepenultimate positions of N—(N1, N2, and N3) and C—(C1, C2, and C3) terminals. Peptide2 analysis suggested that hydrophobic property was prominent in the peptides. The C-terminals were prominent in ACE binding for long-chained peptides through interaction with ACE hotspots. Moreover, branched-chain amino acids (BCAA) such as leucine and isoleucine were crucial at the N-terminals. The bulky side chain of BCAA forms a hydrophobic shield that protects the Zn-peptide chelate complex from water attacks. The hydrophobic fence in turn stabilizes the disrupted tetrahedral Zn-coordinate complex of ACE. This finding provided a thorough exploration of how peptide structures are related and what function they play in ACE inhibitory action. The database analysis, therefore, gave a clearer insight and comprehensive understanding into the protein-peptide interactions and provided a mechanistic explanation.