Structure-Based Identification and Design of Angiotensin Converting Enzyme-Inhibitory Peptides from Whey Proteins

Besides their nutritional value, whey protein (WP) peptides
are
food components retaining important pharmacological properties for
controlling hypertension. We herein report how the use of complementary
experimental and theoretical investigations allowed the identification
of novel angiotensin converting enzyme inhibitory (ACEI) peptides
obtained from a WP hydrolysate and addressed the rational design of
even shorter sequences based on molecular pruning. Thus, after bromelain
digestion followed by a 5 kDa cutoff ultrafiltration, WP hydrolysate
with ACEI activity was fractioned by RP-HPLC; 2 out of 23 collected
fractions retained ACEI activity and were analyzed by liquid chromatography–tandem
mass spectrometry (LC–MS/MS). In the face of 128 identified
peptides, molecular docking was carried out to prioritize peptides
and to rationally guide the design of novel shorter and bioactive
sequences. Therefore, 11 peptides, consisting of 3–6 amino
acids and with molecular weights in the range from 399 to 674 Da,
were rationally designed and then purchased to determine the IC50 value. This approach allowed the identification of two novel
peptides: MHI and IAEK with IC50 ACEI values equal to 11.59
and 25.08 μM, respectively. Interestingly, we also confirmed
the well-known ACEI IPAVF with an IC50 equal to 9.09 μM.
In light of these results, this integrated approach could pave the
way for high-throughput screening and identification of new peptides
in dairy products. In addition, the herein proposed ACEI peptides
could be exploited for novel applications both for food production
and pharmaceuticals.