Identification of a novel angiotensin‐I‐converting enzyme inhibitory peptide corresponding to a tryptic fragment of bovine β‐lactoglobulin

Abstract

The angiotensin‐I‐converting enzyme (ACE) inhibitory activity of a tryptic digest of bovine β‐lactoglobulin (β‐lg) was investigated. Intact β‐lg essentially did not inhibit ACE while the tryptic digest gave an 84.3% inhibition of ACE. Peptide material eluting between 20 and 25% acetonitrile during C₁₈ solid‐phase extraction of the β‐lg tryptic digest inhibited ACE by 93.6%. This solid‐phase extraction fraction was shown by mass spectroscopy to contain β‐lg f(142–148). This peptide had an ACE IC₅₀ value of 42.6 μmol/l. The peptide was resistant to further digestion with pepsin and was hydrolysed to a very low extent with chymotrypsin. The contribution of specific amino acid residues within the peptide to ACE inhibitory activity and the potential application of this peptide as a nutraceutical is discussed.