Optimization of Hydrolysis Conditions for the Production of Angiotensin-I Converting Enzyme-Inhibitory Peptides and Isolation of a Novel Peptide from Lizard Fish (<em>Saurida elongata</em>) Muscle Protein Hydrolysate

Abstract

Lizard fish (<em>Saurida elongata</em>) muscle protein was hydrolyzed using neutral protease to produce protein hydrolysate (LFPH), and the hydrolysis conditions were investigated using response-surface methodology. The optimum conditions for producing peptides with the highest angiotensin-I converting enzyme (ACE)-inhibitory activity were the following: enzyme-to-substrate ratio of 10,000 U/g, temperature of 48 °C, pH 7.0, and hydrolysis time of 2 h. Under these conditions, the ACE-inhibitory activity of LFPH and the degree of hydrolysis were 84% and 24%, respectively. A novel ACE-inhibitory peptide was isolated from LFPH using ultrafiltration, Sephadex G-15, and high-performance liquid chromatography. The amino acid sequence of the ACE-inhibitory peptide was identified as Ser-Pro-Arg-Cys-Arg (SPRCR), and its IC₅₀ was 41 ± 1 µM.

Keywords

• ACE-inhibitory peptide
• lizard fish
• enzymatic hydrolysis
• response surface methodology
• isolation