Preparation and characterization of novel bioactive peptides responsible far angiotensin I-converting enzyme inhibition from wheat germ

Reported is the preparation of wheat germ (WG) hydrolyzate with potent angiotensin I-converting enzyme (ACE) inhibitory activity, and the characterization of peptides responsible for ACE inhibition. Successful hydrolyzate with the most potent ACE inhibitory activity was obtained by 0.5 wt. %-8 h Bacillus licheniformis alkaline protease hydrolysis after 3.0 wt. %-3 h α-amylase treatment of defatted WG (IC₅₀; 0.37 mg protein ml^-1). The activity of WG hydrolyzate was markedly increased by ODS and subsequent AG50W purifications (IC₅₀; 0.018 mg protein ml^-1). As a result of isolations by high performance liquid chromatographies, 16 peptides with the IC₅₀ value of less than 20 μM, composed of 2-7 amino acid residues were identified from the WG hydrolyzate. Judging from the high content (260 mg in 100 g of AG50W fraction) and powerful ACE inhibitory activity (IC₅₀; 0.48 μM), Ile-Val-Tyr was identified as a main contributor to the ACE inhibition of the hydrolyzate.