Purification and Characterization of Angiotensin I Converting Enzyme Inhibitory Peptide from Sand eel Protein Hydrolysates

Abstract

Among the mechanisms associated with hypertension, angiotensin I converting enzyme (ACE) plays an important role in the regulation of blood pressure. The purpose of this study is purification and characterization of an ACE inhibitory peptide derived from enzymatic hydrolysates of sand eel (Hypoptychus dybowskii) protein. Among six hydrolysates, the trypsin hydrolysate had the highest ACE inhibitory activity. A peptide with the strongest ACE inhibitory activity was isolated from the trypsin hydrolysate using consecutive chromatography. The IC50 value of the purified ACE inhibitory peptide was 89.3 μM. Amino acid sequence of the purified peptide was identified to be Pro-Asp-His-Gly-Leu-Tyr-Val, with molecular weight of 907 Da and the Lineweaver-Burk plots suggest that it acts as a competitive inhibitor against ACE. Taken together, these results suggest that sand eel protein hydrolysate are a satisfactory source to inhibit ACE with the potential applications in physiologically functional foods with antihypertensive activity.