ARS | Publication request: Molecular characterization of Ara h 1 before and after thermal processing.

Submitted to: Allergy and Immunology Meeting American Academy
Publication Type: Abstract Only
Publication Acceptance Date: November 22, 2010
Publication Date: March 20, 2011
Citation: Mattison, C.P., Grimm, C.C., Wei, .H. 2011. Molecular characterization of Ara h 1 before and after thermal processing. Poster presented at Allergy and Immunology Meeting American Academy.

Technical Abstract: Heating and other processing techniques can alter food allergens depending upon the method and matrix involved. The increased allergenicity of Ara h 1 protein isolated from roasted peanuts is thought to be caused, at least in part, by chemical modifications. To identify what specific modifications are responsible for increased stability, and recognition by IgE after thermal processing, we are characterizing the roasting-induced molecular changes of the Ara h 1 protein. Ara h 1 was isolated from raw and roasted peanuts, reduced with DTT, alkylated with iodoacetamide, digested with trypsin; and analyzed by liquid chromatrography coupled with mass-spectrometry on a Waters nano-Acquity UPLC, Xevo QTof, and PLGS software. Additional rounds of analysis were performed on intact and digested Ara h 1 using an Agilent nano-LC with Agilent 1200 nano-pumps, and a 6500 Q-Tof LC with the resulting spectra analyzed by Spectrum Mill software. We achieved greater than 60 percent sequence coverage of Ara h 1 isolated from either raw or roasted peanuts, and find at least 16 peptides that are unique to Ara h 1 isolated from roasted peanuts. We detect peptide modification differences between Ara h 1 isolated from raw and roasted peanuts, and the protein modifications we observed included, N-linked glycosylation, hydroxyproline, and carbamylated lysine residues. Some of these modifications were found within the context of previously characterized IgE epitopes. We have detected several chemical modifications on Ara h 1 protein isolated from raw and roasted peanuts that may be responsible for differences in IgE binding and immunogenicity.