Molecular characterization, B-cell linear epitopes identification and key amino acids selection of the sesame...

Ses i 5 is an important sesame allergen and no studies have been reported on the epitope identification of this allergen. Epitopes are the antigenic determinants on the surface of allergens, which are the basis of intensive study on protein antigenicity. In this paper, we analyzed the secondary structure, tertiary structure, hydrophilicity, antigenic index, flexibility, surface accessibility, and homology of the Ses i 5. In addition, we designed and synthesized overlapping peptides covering the entire amino acid sequence of Ses i 5, each overlapping peptide contains 15 amino acids with 5 amino acid repeats. The IgE binding capacity of each peptide was assessed by immune slot blot microarray. Ultimately, we identified seven B-cell linear epitopes of Ses i 5. Furthermore, the key amino acids of Ses i 5 were predicted and mutated to alanine, the changes in the IgE-binding capacity of the mutated peptides were assessed by indirect competition-ELISA (ic-ELISA). At last glycine 104 was identified as the key amino acid for IgE binding in Ses i 5. These studies will contribute to the deep study of molecular characterization and more information on epitopes of Ses i 5, which will benefit for the further understanding of the sesame allergen.