Lactokinins: Whey protein-derived ACE inhibitory peptides

Angiotensin-I-converting enzyme (ACE) has been classically associated with the renin-angiotensin system which regulates peripheral blood pressure. Pep tides derived from the major whey proteins, i. e. alpha-lactalbumin (alpha- 1a) and beta-lactoglobulin (beta-1g) in addition to bovine serum albumin (B SA), inhibit ACE. Some of these inhibitory peptides, i.e. alpha-lactorphin (alpha-1a f(50-53)), beta-lactorphin (beta-1g f(102-105)), beta-lactotensin (beta-1g f(146-149) and albutensin A (BSA f(208-216)), have other bioactiv ities. The most potent lactokinin reported to date, (beta-1g f(142-148)), h as an ACE IC50 of 42.6 mu mol/l. While they do not have the inhibitory pote ncy of synthetic drugs commonly used in the treatment of hypertension, thes e naturally occurring peptides may represent nutraceutical/ functional food ingredients for the prevention/treatment of high blood pressure. Studies w ith gastric and pancreatic proteinase digests of whey proteins indicate tha t enzyme specificity rather than extent of hydrolysis dictates the ACE inhi bitory potency of whey hydrolysates.