The ACE inhibitory activity of an alkaline protease hydrolyzate from sardine muscle did not change after being treated by gastrointestinal proteases (IC50 = 0. 082 mg protein/ml). Eleven new ACE inhibitory peptides, constructed with 2 to 4 amino acid residues, were isolated from the hydrolyzate. The ACE inhibitory activity of each was mostly below 100μM of IC50 value ; the maximal inhibitory activity was observed for Lys-Trp (IC50 = 1. 63 μM). The isolated peptides inhibited ACE competitively, except for Met-Tyr with non-competitive inhibition. As the result of sequence homology, Arg-Val-Tyr isolated from the hydrolyzate was found in the primary structure of angiotensins I, II, and III, and of des Asp-angiotensin I.
Japan Society for Bioscience, Biotechnology, and Agrochemistry