Angiotensin I converting enzyme-inhibitory dipeptides in an alkaline protease hydrolysate of whey protein
1998
Eto, Y. (Chukyo Women's Univ., Obu, Aichi (Japan)) | Ito, T. | Nishioka, S.
This study was an attempt to isolate and identify the short-chain peptides which inhibit angiotensin I converting enzyme (ACE) from an enzymatic hydrolysate of whey protein. Four ACE-inhibitory peptides were isolated from the hydrolysate (WPH) of whey protein isolate (Isolac) obtained using alkaline proteases (Bacillus subtilis protease N and porcine pancreatic trypsin). The ACE-inhibitory peptides were purified to homogeneity from the WPH by gel filtration on a Toyopearl HW-40 column, reverse-phase HPLC on a Asahipak ODP-50 4E column and a SMART system using muRPC C2/C18 SC 2.1/10. The amino acid sequences of four peptides identified by Edman degradation were Phe-Leu, Va1-Tyr, Ile-Leu and Va1-Phe, and their IC50 values (the concentration of the peptide required to inhibit 50% of the ACE activity) for ACE from rabbit lung were 16.0, 17.7, 21.2, and 55.5 muM, respectively. Among these dipeptides, Phe-Leu and Ile-Leu were found for the first time in food protein hydrolysate. Although the digestive resistance of these peptides has not yet been clarified, the present results suggest the potential application of the WPH as an ingredient of physiologically functional food to prevent hypertension
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