Location: Healthy Processed Foods ResearchTitle: Purification and characterization of black walnut (Juglans nigra) Allergen, Jug n 4 Author
|Fan, Yuting - Jiangnan University|
|Yi, Jiang - Shenzhen University|
|Lyu, Shu-chen - Stanford University|
|Nadeau, Kari - Stanford University|
|Thomas, Andrew - University Of Missouri|
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/11/2016
Publication Date: 12/12/2016
Citation: Zhang, Y., Du, W., Fan, Y., Yi, J., Lyu, S., Nadeau, K.C., Thomas, A.L., McHugh, T.H. 2016. Purification and characterization of black walnut (Juglans nigra) Allergen, Jug n 4. Journal of Agricultural and Food Chemistry. 65(2):454-462.
Interpretive Summary: American walnut is also known as black walnut or eastern black walnut. It is a high-value crop best known for its use as lumber and veneer. The nut shell, oil and other part of black walnut, including the bark which is poisonous, all has been used in various industries and in traditional medicine. As a food product, the kernels of black walnuts have been providing food for wildlife and humans for centuries. In recent years, black walnut is getting popular with consumers due to its rich aromatic flavor and its ample oil and protein contents. As a tree nut, it belongs to one of the eight food groups that cause the majority of food allergies in the US. However, information about walnut allergens is limited and American walnut legumin has not been studied. This study report the isolation of walnut legumin and the identification of this protein as a new walnut allergen. The reported result and the reagents generated may be used to understand the allergenicity of walnut allergens and enhance the marketability of the tree nut in the future.
Technical Abstract: Tree nuts as a group have caused a significant number of cases of fatal anaphylactic reactions. In a large scale study of US peanut and tree nut allergy cases with 5149 patients, walnuts were the leading cause of allergic reactions. The purpose of this study was to purify and characterize potential food allergens from black walnut. Reported here is a purification scheme of the 11S legumin protein from black walnuts by ammonium sulfate precipitation, cold precipitation, and anion exchange and size exclusion chromatography. Reducing SDS-PAGE analysis indicated that purified legumin consists of 2 major bands. The 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 consists of a known conserved protease recognition motif, NGXEET. Western blot experiments revealed that 28% of the sera from 25 patients with double-blind, placebo controlled clinical walnut allergy contained IgE antibodies specific to black walnut legumin, indicating that it is a walnut allergen. Data and reagent obtained in this study may facilitate the understanding of the allergenicity relevance of seed storage proteins in tree nuts and their cross-reactivity.