imidazolone and Nut-Hypersensitivity

Raw and roasted cashew nut extracts were evaluated for protein modifications by mass spectrometry. Independent modifications on the Arg-111 residue of Ana o 3 were observed in roasted but not raw cashew nuts. The mass changes of 72.0064 or 53.9529 Da are consistent with the formation of carboxyethyl and hydroimidazolone modifications at the Arg-111 residue. These same modifications were observed in Ana o 3 purified from roasted but not raw cashew nuts, albeit at a relatively low occurrence. 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 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 a reducing agent. Only minor differences in IgE binding to Ana o 3 were observed by ELISA among a cohort of cashew-allergic patient sera.

Topics: Anacardium; Antigens, Plant; Arginine; Circular Dichroism; Dynamic Light Scattering; Enzyme-Linked Immunosorbent Assay; Food Handling; Heating; Humans; Imidazoles; Immune Sera; Immunoglobulin E; Nut Hypersensitivity; Nuts; Particle Size; Plant Proteins; Protein Conformation; Trypsin