A novel ACE-inhibitory hexapeptide from camellia glutelin-2 hydrolysates: Identification, characterization and stability profiles under different food processing conditions

Abstract A novel ACE-inhibitory hexapeptide (Gly-Tyr-Gly-Tyr-Asn-Tyr) was identified in camellia cake glutelin-2 hydrolysates through Sephadex G-15 gel chromatography and RP-HPLC separation, UPLC-ESI-MS/MS analysis and in silico screening. This peptide sequence was chemically synthesized and the combination pattern between GYGYNY and angiotensin-I converting enzyme was simulated using molecular docking. Moreover, the stability profiles of GYGYNY against different pH and metal ions, heating, and gastrointestinal enzymes digestion were studied. Results demonstrated that GYGYNY was a noncompetitive inhibitor of ACE with a high inhibition activity (IC50: 384 μmol/L), because it could bind to eight active sites of ACE (but not the key active sites) via short hydrogen bonds. The predicted amphiphilicity and isoelectric point of GYGYNY were 2.53 and pH 5.87, respectively. Moreover, ACE-inhibitory activity of GYGYNY is relatively stable from pH 3.0 to pH 11.0 (except pH 5.0), or under most of pasteurization conditions, or when subjected to simulated gastrointestinal digestion. But ACE-inhibitory activity of GYGYNY was significantly decreased (P