Title: Identification of Maillard reaction induced chemical modifications on Ara h 1 Authors
Submitted to: Allergy and Immunology Meeting American Academy
Publication Type: Abstract Only
Publication Acceptance Date: November 29, 2011
Publication Date: March 5, 2012
Citation: Mattison, C.P., Grimm, C.C., Desormeaux, W.A., Ruan, S., Tarver, M.R., Hurlburt, B.K., Cheng, H., Maleki, S.J. 2012. Identification of Maillard reaction induced chemical modifications on Ara h 1. Abstract presented at Allergy and Immunology Meeting American Academy. Technical Abstract: The Maillard reaction is a non-enzymatic glycation reaction between proteins and reducing sugars that can modify nut allergens during thermal processing. These modifications can alter the structural and immunological properties of these allergens, and may result in increased IgE binding. Here, we present data identifying and characterizing specific Maillard reaction-dependent modifications on recombinant Ara h 1 protein. Recombinant Ara h 1 protein produced in E. coli was purified by ion exchange chromatography, and incubated in the presence of reducing sugars at elevated temperature in a simulated roasting model. Samples were analyzed by immunoblot with Maillard reaction-specific antibodies, peanut allergic patient sera, and liquid chromatography coupled with mass spectrometry (LC-MS). We find that recombinant Ara h 1 has increased reaction with anti-carboxymethyl lysine, other Maillard reaction specific antibodies, and IgE from peanut allergic patient sera after incubation with sugar. We observed greater than 80% coverage of the recombinant Ara h 1 protein by LC-MS analysis. Several Maillard reaction-dependent modifications; including carboxymethylation, carboxyethylation, malondialdehyde, and pyrrolysine on the Ara h 1 protein were detected on specific peptides by the LC-MS analysis. Some of the modifications were found to lie within or near previously characterized linear IgE epitopes on Ara h 1. Identification of the Maillard reaction induced chemical modifications on specific peptides within Ara h 1, may help explain the elevated recognition by IgE, and the increased protein stability of peanut proteins after thermal processing. Identification of the sites of protein modification can be used to guide processing steps that can reduce or eliminate peanut allergens.