Objective The olecranon peach is known as one of the characteristic fruits in Lingnan region because of its good flavor and quality, and it is listed as "The top ten best fruits in Lingnan". However, less studies on its allergens have been reported. By analyzing the epitope of allergen protein, it would provide a research basis for the preparation of the recombinant antigen of the allergen, and also provide a research basis for explaining the characteristic changes and sensitization characteristics of the allergen in the process of food processing.
Method Phosphate buffer saline was used to extract the crude protein from the lyophilized powder of olecranon peach, and the allergens in the crude protein were identified by SDS-PAGE protein electrophoresis and analyzed by mass spectrometry. The allergens were screened and compared by the protein database of UniProt, and the physicochemical properties, spatial structure and antigenic epitopes of the allergens were analyzed by bioinformatics methods.
Result Seven kinds of allergenic proteins including A0A251RBV3, P86888, M5X697, M5WV03, M5WTQ8, Q2I6V8, and Q9LED1 were identified from olecranon peach, which belonged to the four classes of allergenic proteins, namely, pathogenesis-related proteins (Pru p 1), thaumatin-like proteins (Pru p 2), non-specific lipid transfer proteins (Pru p 3) and gibberellin-regulated proteins (Pru p 7). The seven kinds of allergenic proteins in olecranon peach had high stability, their molecular weight is 6.91-26.04 kD, with the aliphatic index between 29.37 and 81.54. M5WTQ8 and Q2I6V8 allergen proteins were acidic proteins, while the remaining allergen proteins were alkaline proteins. Except for Q9LED1 protein, all other allergen proteins were hydrophilic proteins. The regions with antigenic epitopes, hydrophilicity and flexibility greater than 0 and surface accessibility greater than 1 were screened, and regions with low protein bonding energy were analyzed by binding the secondary and tertiary structures of proteins to obtain the antigenic epitopes of allergens, including Pru p1 (EIP, GSQ, KEN, NL, KG, EIK, HPD), Pru p 2 (TGDQKPQ, SP, NQ, PPNDKPETCPPT, DDKSS, RP), Pru p 3 (RT, VN) and Pru p 7 (AGY, GTYGN, LKNSKGN).
Conclusion By analyzing the structure, hydrophilicity, surface accessibility, flexibility and antigen index of olecranon peach, multiple epitopes of 7 allergens are obtained, which can provide a research basis for the sensitization characteristics of olecranon peach allergens in food processing.
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