Purification and characterization of angiotensin I-converting enzyme inhibitors from sour milk

The inhibitory activity of angiotensin I-converting Enzyme in milk increased during fermentation with the Calpis sour milk starter containing Lactobacillus helveticus and Saccharomyces cerevisiae. Two kinds of Peptides inhibitory to angiotensin I-converting Enzyme were purified from the sour milk by using four-step HPLC. The amino acid sequences of these inhibitors were identified as Val-Pro-Pro and Ile-Pro-Pro. The concentrations of Peptides providing 50% inhibition of angiotensin I-converting Enzyme were 9 and 5 microM, respectively. Most of the inhibitory activity in sour milk was attributed to these two Peptides.