Abstract

Tree nuts as a group cause a significant number of fatal anaphylactic reactions to foods. Walnuts (Juglans spp.) were one of the leading causes of allergic reactions to tree nuts in the US and Japan. The purpose of this study was to purify and characterize potential food allergens from black walnut. Here, we report the isolation of the black walnuts allergen Jug n 4 (an 11S globulin) by ammonium sulfate precipitation, and hydrophobic interaction and size exclusion chromatography. Reducing SDS-PAGE analysis indicated that purified Jug n 4 consists of 3 major bands. N-terminal sequencing data of these bands indicated that they were the results of a post-transcriptional protease cleavage of the mature protein at a site that consists of a known conserved protease recognition motif, NGXEET. Western blot experiments revealed that 32% of the sera from 25 patients with double-blind, placebo-controlled clinical walnut allergy contained IgE antibodies that recognized Jug n 4, indicating that it is a walnut allergen. Identifying this and additional allergens may facilitate the understanding of the allergenicity of seed storage proteins in tree nuts and their cross-reactivity.

View details for DOI 10.1021/acs.jafc.6b04387

View details for PubMedID 27936684