Research on the screening and inhibition mechanism of angiotensin I-converting enzyme (ACE) inhibitory peptides from tuna dark muscle

The rapid screening of angiotensin I-converting enzyme (ACE) inhibitory peptides (ACEIPs) from protein hydrolysates remains a challenge in current researches. The current study presents the development of an efficient affinity medium (AOPAN–ACE) consisting of ACE immobilized on the surface of electrostatically spun polyacrylonitrile nanofibrous membranes for the efficient screening of ACEIPs. The application of this affinity medium followed by liquid chromatography–tandem mass spectrometry analysis resulted in the successful screening and identification of 60 potential ACEIPs from protein hydrolysates of tuna dark muscle. Notably, the application of PeptideRanker, pLM4ACE, and molecular docking approaches resulted in the screening and identification of a novel ACEIP FPPDVA. Furthermore, the peptide FPPDVA was synthesized using the solid-phase method, and its IC50 value on ACE was determined to be 87.11 ± 1.02 μM. Molecular docking analysis suggested that the ACEIP of the peptide FPPDVA is attributable to the formation of hydrogen bonds with the S1 active site (Ala354 and Tyr523) of ACE and metal–ligand bonds with Zn2+. In addition, molecular dynamics simulations revealed that the peptide FPPDVA formed a stable complex with ACE and was consistently localized within the active pocket of ACE over a simulation duration of 100 ns without being displaced from the active site. Lineweaver–Burk analysis further confirmed that the peptide FPPDVA exhibited mixed mode of inhibition against ACE. Overall, the affinity medium developed in the current study is potentially useful for highly efficient screening of ACEIPs, and the novel ACEIP FPPDVA identified herein is a promising functional food ingredient for antihypertensive application.