Inhibition strength of short peptides derived from an ACE inhibitory peptide.

A series of peptides, derived from an ACE inhibitory peptide (VTVNPYKWLP) found in our previous work, were synthesized. Their half maximal inhibition concentrations (IC(50)) for ACE inhibition have been determined. The effect of amino acid sequence on ACE inhibition was discussed on the basis of IC(50) of the synthetic peptides, and the following characteristics of the ACE inhibitory peptide have been clarified. First, the active portion of this peptide for ACE inhibition is KW. Second, the amino acid sequences near this dipeptide (KW) have a strong effect on the inhibitory activity. Especially, the proline residue in the C-terminal end strongly enhanced ACE inhibition. It should be noted that the IC(50) value of KWLP (5.5 μM) is the same as the ACE inhibitory peptide (VTVNPYKWLP) and that the IC(50) value of KW is 7.8 μM. The stability and absorption efficiency in vivo would be significantly improved by shortening the peptide length from 10 amino acids to four amino acids or two amino acids.