Identification of casein-derived peptides that inhibit the prolyl endoprotease from Eurygaster integriceps

The prolyl endoprotease (PEP) from Eurygaster integriceps Puton (Sunn pest) causes significant damage to wheat crops in regions of North Africa, Eastern Europe, and Western Asia with an annual cost over one million USD. Previous research resulted in isolation, characterization, and recombinant production of this gluten-degrading enzyme. The current goal is to identify safe, affordable inhibitors that could potentially reduce gluten damage. A recent article showed that peptides present in Lactobacillus digested casein samples were able to inhibit the human form of PEP. In this research, these methods are adapted to test whether casein peptides are able to inhibit the Sunn pest PEP. The results indicate that samples of whole, alpha-, and beta-caseins digested for three hours are able to inhibit the enzyme by 18%, 28%, and 18%, respectively. Future work should include isolation and sequencing of inhibitory peptides and assessment of the ability reduce damage to wheat gluten.