Isolation and characterization of angiotensin I-converting enzyme inhibitory peptides from wheat gliadin hydrolysate.

Angiotensin I-converting enzyme (ACE) inhibitory peptide was isolated from wheat gliadin hydrolysate prepared with acid protease. Consecutive purification methods were used for peptide isolation including ion-exchange chromatography, size-exclusion chromatography, and reverse-phase high-performance liquid chromatography. The amino acid sequence of this peptide was identified as Ile-Ala-Pro, and the ACE inhibitory activity (IC50 value) was 2.7 microM. The hypotensive activity of Ile-Ala-Pro on spontaneously hypertensive rats was investigated. This peptide inhibited the hypertensive activity of angiotensin I with intravenous injection, and decreased the blood pressure significantly with intraperitoneal administration.