Glutamine and lysine as common residues from epitopes on -lactalbumin and -lactoglobulin from cow milk identified by phage display technology

Cow milk is an important source of food protein for children; however, it could lead to allergy, especially for infants. alpha-Lactalbumin (alpha-LA) and beta-lactoglobulin (beta-LG) from whey protein make up a relatively high proportion of milk proteins and have received wide-spread attention as major allergens in milk. However, few studies have identified the epitopes of both pro-teins simultaneously. In this study, ImmunoCAP and indirect ELISA were first used for detection of sIgE to screen sera from allergic patients with high binding capacity for alpha-LA and beta-LG. Subsequently, the mimo -topes was biopanned by phage display technology and bioinformatics and 17 mimic peptide sequences were obtained. Aligned with the sequences of alpha-LA or beta-LG, we identified one linear epitope on alpha-LA at AA 11-26 and 5 linear epitopes on beta-LG at AA 9-29, AA 45-57, AA 77-80, AA 98-101, and AA 121-135, respectively. Meanwhile, the 8 conformational epitopes and their distributions of alpha-LA and beta-LG were located using the Pepitope Server. Finally, glutamine and lysine were determined as common AA residues for the conforma-tional epitopes both on alpha-LA and beta-LG. Moreover, we found the addition of mouse anti-human IgE during the biopanning process did not significantly affect the identification of the epitopes.