Purification and characterization of a novel angiotensin I-converting enzyme inhibitory peptide derived from abalone (Haliotis discus hannai Ino) gonads

Abalone gonads were hydrolyzed using alcalase followed by papain to produce angiotensin I-converting enzyme (ACE) inhibitory peptides. Gel filtration column chromatography analysis showed that the molecular weight of the fraction with high ACE inhibitory activity was below 1 kDa, which occupied 93.1 % of total hydrolysate. The ACE inhibitory peptide was purified by a series of column chromatographies, and the sequence of purified peptide was further identified as Ala-Met-Asn (AMN) by automated Edman degradation method. The triple peptide was then synthesized and had an ACE inhibitory activity with IC50 value of 106.24 mu g/mL. After gastrointestinal digestion, the peptide still remained bioactivity. Lineweaver-Burk plots indicated that AMN acts as a non-competitive inhibitor against ACE. Our present study suggested that AMN derived from abalone gonad by-products may be used as an ideal nutrient for development of functional foods.