A novel ACE inhibitory peptide from Gadus morhua skin: Isolation, characterization and antihypertensive mechanisms

This study aimed to develop a novel ACE inhibitory peptide from cod skin with antihypertensive activity. Cod skin collagen hydrolysate was prepared by stepwise enzymatic hydrolysis using Collagen hydrolase followed by flavourzyme. The hydrolysate was purified by ultrafiltration, Sephadex G-25 chromatography, and preparative HPLC. A new ACE inhibitory peptide, GPAGPSGP (638.67 Da), was identified with an IC 50 of 179 ± 12 μM, retaining 97.49 % activity after simulated gastrointestinal digestion. Mixed-type inhibition was confirmed by kinetic analysis. Molecular docking revealed a binding energy of −10.1 kcal/mol for the GPAGPSGP–ACE interaction, indicating hydrophobic and polar residues mediate side-chain interactions in the ACE active site. The ACE-inhibitory peptide obtained from cod skin by two-enzyme hydrolysis showed strong activity, supporting its potential use in functional foods for hypertension management. • Double-enzymatic stepwise hydrolysis enhanced hydrolysis efficiency and ACE-inhibitory activity. • A novel ACE inhibitory peptide GPAGPSGP with a non-competitive binding mode was identified. • Molecular docking revealed key binding interactions between GPAGPSGP and the ACE active site.