Purification and charicterization of angiotensin I-converting enzyme (ACE) inhibitory peptides with specific structure X-Pro

Abstract

This study aimed to specifically prepare angiotensin I-converting enzyme (ACE) inhibitory peptides rich in C-terminal proline from oyster proteins using chymotrypsin and proline-specific endopeptidases (PSEases). The hydrolysates were purified with Sephadex G25, Superdex™ 30 Increase 10/300 GL gel filtration chromatography and reverse-phase high-performance liquid chromatography (RP-HPLC). The ACE inhibitory IC50 of purified fraction (G1E1C1) was 0.032 ± 0.003 mg/mL. According to ESI–MS and ESI–MS/MS analyses, there were three novel ACE inhibitory peptides in G1E1C1 fraction. Their sequences were Ser-Ala-Pro, Ala-Met-Pro and Thr-Ser-Gly-Pro. Molecular docking of peptides to ACE was studied. Metal–acceptor interactions and conventional hydrogen bonds greatly promoted the stability of peptides to ACE interaction. Pyrrole ring of proline may lead to higher inhibitory activity of peptides. It easily formed a Pi–alkyl interaction with aromatic ring residues (His353, His387, His513, and Phe512). Pi interactions may promote the effect of peptides on ACE. Also, C atom adjacent to the N atom of the pyrrole ring easily formed a carbon hydrogen bond with Ala354. The research discovered three novel ACE inhibitory peptides and provided a method to obtain ACE inhibitory peptides with specific structure X-Pro. The research result played an important role in revealing the structure–activity relationship of ACE inhibitory peptides and designing novel peptides with enhanced biological activity.