Separation, Purification, and Identification of Angiotensin I–Converting Enzyme Inhibitory Peptides from Walnut ( Juglans regia L.) Hydrolyzate.

Walnut proteins were hydrolyzed with pepsin, alcalase, and papain. A peptide that strongly inhibits angiotensin I–converting enzyme was isolated and purified from walnut protein hydrolyzates via ultrafiltration, Sephadex G-25, Superdex™ Peptide 10/300 GL, and reversed phase high-performance liquid chromatography. Thein vitroinhibition of angiotensin I–converting enzyme was used as an indicator. The molecular structure and sequences of the angiotensin I–converting enzyme inhibitory peptides were identified through mass spectrometry and amino acid sequencing. The angiotensin I–converting enzyme inhibitory peptide from the walnut hydrolyzate was identified as Tyr-Glu-Pro (YEP) and its median inhibitory concentration was 0.29μmol/L. [ABSTRACT FROM AUTHOR]