Angiotensin I-Converting Enzyme Inhibitory Peptides Derived from Bonito Bowels Autolysate

Six angiotensin I-converting enzyme inhibitory peptides were isolated from a bonito bowels autolysate. Their amino acids were sequenced as Tyr-Arg-Pro-Tyr, Gly-His-Phe, Val-Arg-Pro, Ile-Lys-Pro, Leu-Arg-Pro, and Ile-Arg-Pro. Peptides having corresponding amino acid sequences were synthesized by a solid-phase method and their inhibition of the activity measured. IC₅₀ of these peptides were estimated to be 320, 1100, 2.2, 2.5, 1.0, and 1.8 μM, respectively. The role of carboxyl terminal proline residues on the inhibition is discussed.