Structure and activity of angiotensin I converting enzyme inhibitory peptides from sake and sake lees.

Nine peptides to inhibit angiotensin I converting enzyme (ACE) were isolated from sake and sake lees. They were short peptides with 5 or fewer amino acid residues, and many of them had a tryptophan or tyrosine residue at the C-terminus. We synthesized the peptide fragments of IYPRY and YGGY, and measured their inhibitory activity. As a result, we have concluded that hydrophobic amino acids in the sequence and amino acid at C-terminus had an important role in the inhibition. When digested with pepsin and pancreatin, YGGY lost its inhibitory activity but IYPRY maintained its activity. YGGY and IYPRY were orally administered to spontaneously hypertensive rats (SHR) at the dose of 100 mg/kg. YGGY didn't change the blood pressure of SHR, but IYPRY reduced their blood pressure. The hypotensive effect of IYPRY continued for 30 h after administration. Also, three dipeptides among the IYPRY fragments, IY, YP and RY, had hypotensive effects, and the effect of RY continued for 30 h after administration.