Characterization of Novel ACE-Inhibitory Peptides from <i>Nemopilema nomurai </i>Jellyfish Venom Hydrolysate: In Vitro and In Silico Approaches

The venom of Nemopilema nomurai jellyfish represents a promising source of bioactive compounds with potential pharmacological applications. In our previous work, we iden-tified two novel angiotensin-converting enzyme (ACE) inhibitory peptides—IVGRPLANG (896.48 Da) and IGDEPRHQYL (1227.65 Da)—isolated from N. nomurai venom hydroly-sates via papain digestion. In this study, we conducted a detailed biochemical and com-putational characterization of these peptides. The IC₅₀ values were determined to be 23.81 µM for IVGRPLANG and 5.681 µM for IGDEPRHQYL. Kinetic analysis using Lineweav-er–Burk plots revealed that both peptides act as competitive ACE inhibitors, with calcu-lated inhibition constants (Kᵢ) of 51.38 µM and 5.45 µM, respectively. To assess the struc-tural stability of the ACE–peptide complexes, molecular dynamics simulations were per-formed. Root mean square deviation (RMSD) and root mean square fluctuation (RMSF) analyses provided insights into complex stability, while interaction fraction analysis elu-cidated key bond types and residue–ligand contacts involved in binding. Furthermore, a network pharmacology approach was employed to predict therapeutic targets within the renin–angiotensin–aldosterone system (RAAS). Eleven target proteins were identified: IVGRPLANG was associated with REN, ACE, CTSB, CTSS, and AGTR2; IGDEPRHQYL was linked to REN, AGT, AGTR1, AGTR2, KNG1, and BDKR2. Molecular docking anal-yses using HADDOCK software were conducted for all targets to evaluate binding affini-ties, providing further insight into the peptides’ therapeutic potential.