Identification, Characterization and Epitopes Prediction of an Almond Allergen Pru du 8 Fragment.

Pru du 8 is a 31 kDa antibacterial protein and officially recognized almond allergen, but its native form in mature almonds has not been characterized, and no effective extraction method has been established. In this study, we successfully isolated a high-purity (>95%) 15 kDa protein from almond extract using a one-step chromatographic approach. Mass spectrometry identified this protein as a fragment of Pru du 8. The purified 15 kDa fragment exhibited strong IgE-binding activity with sera from almond-allergic patients, and its IgE-binding specificity was confirmed by negative reactivity with non-atopic control blood serum. Structural characterization by circular dichroism and ultraviolet spectroscopy revealed that the fragment adopts a predominantly α-helical, compact fold. Furthermore, computational epitope prediction identified key B-cell epitopes on this naturally occurring fragment. This study provides the isolation method for a native Pru du 8 fragment and confirms its allergenic potential, offering a valuable tool for future research on almond allergy.