|LI, YICHEN - Oak Ridge Institute For Science And Education (ORISE)|
|CHIDAL, HEIDI - Biomed Bridge|
|MCCASLIN, DARRELL - University Of Wisconsin|
|Chung, Si Yin|
|BREN-MATTISON, YVETTE - Biomed Bridge|
|WASSERMAN, RICHARD - Allergy Partners Of North Texas Research|
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/14/2016
Publication Date: 1/18/2017
Citation: Mattison, C.P., Grimm, C.C., Li, Y., Chidal, H.J., McCaslin, D.R., Chung, S., Bren-Mattison, Y., Wasserman, R.L. 2017. Identification and characterization of ana o 3 modifications on arginine-111 residue in heated cashew nuts. Journal of Agricultural and Food Chemistry. 65(2):411-420.
Interpretive Summary: Cooking foods can modify the proteins we eat. Heat can alter the size, shape, and other characteristics of food proteins. In some cases, these alterations can affect how our bodies digest and otherwise process the nutrients we ingest. Cashew nuts contain proteins that can cause food allergy. Cashew nuts are often used in heated dishes such as stir fry, and we looked for changes in the proteins that can cause food allergy when cashew nuts are heated. We observed changes from heated but not raw cashew nuts in one of the cashew nut proteins, the Ana o 3 protein, that can cause allergy . Structural studies of the unmodified and modified Ana o 3 protein indicated that was no large difference in the proteins characteristics. The stability of Ana o 3 purified from raw and roasted cashew nuts to digestion by the intestinal protease trypsin, was also similar. We did not observe differences in IgE antibody, the type antibody that can cause allergic reactions, binding to Ana o 3 from cashew allergic patient sera. for the first time, we have identified and characterized a heating-induced modification formed in nuts in the cashew nut allergen Ana o 3.
Technical Abstract: Heating foods can alter the physical, chemical, and biological characteristics of the proteins we consume. Raw and roasted cashew nut extracts were evaluated for allergen modifications by mass-spectrometry. We did not identify modifications on Ana o 1 or Ana o 2, but we observed two independent modifications on the Arg-111 residue of Ana o 3 in roasted but not raw cashew nuts. The mass changes of 72.0064 or 53.9529 Da we observed are consistent with formation of carboxyethyl and hydroimidazolone modifications at the Arg111-residue. The modified proteins were observed at a relatively low occurrence. We observed these same modifications in Ana o 3 purified from roasted cashew nuts. Circular dichroism indicated that Ana o 3 purified from raw and roasted cashew nuts had similar secondary structure, and dynamic light scattering analysis indicated there was no observable difference in Ana o 3 particle size. The stability of Ana o 3 purified from raw and roasted cashew nuts to trypsin was similar in the absence of or following treatment with the reducing agent dithiothreitol. We did not observe differences in IgE binding to Ana o 3 by ELISA among a cohort of cashew allergic patient sera demonstrated to recognize Ana o 3 by immunoblot. We have identified for the first time a heating-induced modification formed in situ on the cashew nut allergen Ana o 3.