In silico identification of antidiabetic and hypotensive potential bioactive peptides from the sheep milk proteins—a molecular docking study

An in silico approach was used for hydrolysis of sheep milk proteins (α-s1, α-s2, β-casein, κ-Cn, α-lactalbumin, and β-lactoglobulin) by gastrointestinal enzymes in order to generate bioactive peptides (BAPs) that can inhibit ACE and DPP-IV. Sheep milk proteins showed higher similarity with goat milk proteins. These data were acquired via the Clustal Omega tool to perform sequence alignment analysis. The BIOPEP-UWM database was used to examine the ability of sheep milk protein sequences to generate BAPs, which included a description of their potential bioactivity as well as the frequency of fragments with specified activities. Using the "Enzyme(s) action" tool (BIOPEP-UWM), digestive enzymes pepsin, trypsin, and chymotrypsin, and three enzyme combinations were selected to computationally hydrolyze milk proteins for obtaining information about ACE and DPP-IV inhibitory peptides. Other online programs were used to test potential peptides for bioactivity, toxicity, and physicochemical properties. BAPs produced from PTC-hydrolyzed proteins were analyzed using a peptide ranker, and their inhibitory effects on ACE and DPP-IV were determined using molecular docking. Consequently, the results of molecular docking analysis show that the peptide PSGAW (αS1-Cn f155-159) binds to DPP-IV with binding energy (-8.9 kcal/mol). But in the case of ACE, two potential BAPs were selected: QPPQPL (β-Cn f161-166) and PSGAW. These two BAPs revealed a higher binding affinity for ACE with a binding energy of -9.8 kcal/mol. Thus, the results showed that sheep milk proteins were a promising source of antidiabetic and hypotensive peptides. However, experimental and pre-clinical studies are necessary to assay their therapeutic effects. PRACTICAL APPLICATIONS: Sheep milk proteins are known as a high-quality milk protein resource. Effective enzymatic hydrolysis of sheep milk proteins can release bioactive peptides and also release potential ACE and DPP-IV inhibitory peptides. This in silico study specifies a theoretical root for sheep milk proteins as a novel source of potential bioactive peptides and may offer guidance for invitro hydrolysis of proteins for the production of bioactive peptides valuable for human consumption.