Abstract: Objective: Antihypertensive peptides with both angiotensin-converting enzyme (ACE) inhibitory activity and ACE2 upregulating activity were prepared from abalone muscle, and their action mechanisms were investigated. Methods: The conditions for the enzymatic hydrolysis of abalone muscle were optimized. The fractions with high in vitro ACE inhibitory activity and ACE2 upregulating activity were selected and purified by sequential ultrafiltration, gel column chromatography, and reverse phase-high performance liquid chromatography (RP-HPLC), and their sequences were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The inhibition type and binding stability were analyzed using molecular docking, inhibition kinetics, and molecular dynamic simulation. Results: A total of 26 antihypertensive peptides were identified through de novo sequencing. Based on molecular docking and binding free energy screening, six peptides were selected: Ala-Gly-Phe (AGF), Ala-Thr-Lys (ATK), Pro-Ile-Ile-Thr-Lys (PIITK), Ala-Lys (AK), Pro-Val-Gly-Arg (PVGR), and Pro-Trp (PW). Among them, PIITK and PVGR exhibited higher ACE inhibitory activity. In terms of ACE2 upregulation, PW showed the most significant effect, followed by PVGR, AK, and ATK. PIITK acted as a competitive ACE inhibitor, while PVGR exhibited mixed-type inhibition. Molecular dynamic simulation results demonstrated that both PIITK-ACE and PVGR-ACE complexes had high binding stability. Conclusion: Our findings provide a theoretical basis for the development and high-value utilization of abalone-based functional foods.

Key words: abalone; antihypertensive peptides; molecular docking; molecular dynamics simulation