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Ara h 1 structure is retained after roasting and is important for enhanced binding to IgE

Authors


Correspondence: Dr. Soheila J. Maleki, Research Chemist; USDA-ARS-SRRC, 1100 Robert E. Lee Boulevard; New Orleans, LA 70124

E-mail: soheila.maleki@ars.usda.gov

Fax: +1-504–286-4430

Abstract

Scope

Ara h 1 from roasted peanut binds higher levels of serum immunoglobulin E than raw peanuts and this is likely due to the Maillard reaction. While Ara h 1 linear IgE epitopes have been mapped, the presence and importance of structural epitopes is not clear.

Methods and results

Mass spectrometry, immunoblot, ELISA, circular dichroism (CD), and structural analysis were used to compare structural and subsequent IgE-binding differences in Ara h 1 purified from raw (N) and roasted peanuts (R) and denatured Ara h 1 (D). Although N and R had similar CD spectra, the latter bound significantly more IgE. Decreased IgE binding was seen with the loss of secondary structure. This same IgE-binding pattern [R > N > D] was seen for the sera of ten peanut allergic patients. While the majority of linear epitopes are located on surface and structured regions of Ara h 1, our study shows that conformational epitopes of Ara h 1 bind better to IgE than linear epitopes.

Conclusion

Enhanced IgE binding to roasted Ara h 1 could be due to alterations such as chemical modifications to individual amino acids or increased epitope exposure. IgE binding is significantly reduced with loss of structure.

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