A Sweet Almond Globulin Multifunctional Peptide: Identification, In Silico Screening, Restraint Mechanisms to Keap1 and ACE, and Antihypertensive and Ferrous Transport Efficiency.

Background: Sweet almond expeller is an abundant protein resource, but there are few studies on multifunctional peptides. The purpose of this study is to improve its application in food and medical industries. Methods: This study investigated the identification, screening, and action mechanisms of antihypertensive peptides with antioxidant and ferrous binding activities derived from sweet almond globulin hydrolysates using intergrade in vitro and in silico methods and an animal model. Results: Eight novel oligopeptides were identified in sweet almond globulin hydrolysates subfraction D; of them, Pro-Met-Tyr-Gly-Gly-Gly-Met-Val (PMYGGGMV) exhibited ACE inhibitory activity (IC(50): 121.16 μmol/L), ferrous binding ability (11.01 mg/g), and quenching capacities on hydroxyl (93.06%) and ABTS radicals (83.67%). The phenolic hydroxyl, amino, and carboxyl groups of PMYGGGMV were linked to Lys511, Tyr520, and Tyr523 in ACE's substrate binding center through four short hydrogen bonds. PMYGGGMV can inhibit the Kelch-like ECH-Associated Protein 1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2) interaction by binding to seven residues of Keap1 (including a key residue, Arg415). The ACE inhibitory and antioxidant activities of PMYGGMY were stable during gastrointestinal digestion. Ferrous chelation did not alter the ACE inhibitory and antihypertensive effects of PMYGGMY, but it reduced its ABTS and hydroxyl radical scavenging ability (p < 0.05). Additionally, PMYGGGMV reduced blood pressure of spontaneous hypertension rates and improved iron absorption across Caco-2 cells (p < 0.05). Conclusions: PMYGGGMV has the potential to prevent oxidative stress, hypertension, and iron deficiency.