Heat-induced conformational changes of Ara h 1, a major peanut allergen, do not affect its allergenic properties

Ara h 1 , a major peanut allergen was isolated, and its structure on secondary, tertiary, and quaternary level at ambient temperature was investigated using spectroscopic and biochemical techniques. Ara h 1 appeared to be a highly structured protein on a secondary level, possesses a clear tertiary f...

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Bibliographic Details
Published in:	The Journal of biological chemistry 1999-02, Vol.274 (8), p.4770-4777
Main Authors:	Koppelman, S.J, Bruijnzeel-Kooman, C.A.F.M, Hessing, M, Jongh, H.H.J. de
Format:	Article
Language:	eng
Subjects:	Adult allergenicity allergens Allergens - chemistry antigen-antibody reactions Antigens, Plant Arachis - chemistry Arachis hypogaea binding Calorimetry, Differential Scanning Chromatography, Gel Circular Dichroism epitopes food allergies Food Chemistry and Microbiology Glycoproteins heat treatment Hot Temperature Humans immunoglobulin E Immunoglobulin E - blood Levensmiddelenchemie en -microbiologie Membrane Proteins molecular conformation peanuts Plant Proteins - chemistry Protein Conformation Spectrophotometry, Ultraviolet VLAG
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Summary:	Ara h 1 , a major peanut allergen was isolated, and its structure on secondary, tertiary, and quaternary level at ambient temperature was investigated using spectroscopic and biochemical techniques. Ara h 1 appeared to be a highly structured protein on a secondary level, possesses a clear tertiary fold, and is present as a trimeric complex. Heat treatment of purified Ara h 1 results in an endothermic, irreversible transition between 80 and 90âÂ°C, leading to an increase in Î²-structures and a concomitant aggregation of the protein. Ara h 1 from peanuts that were heat-treated prior to the purification procedure exhibited a similar denatured state with an increased secondary folding and a decreased solubility. The effect of heat treatment on the in vitro allergenic properties of Ara h 1 was investigated by means of a fluid-phase IgE binding assay using serum from patients with a clinically proven peanut allergy. Ara h 1 purified from peanuts heated at different temperatures exhibited IgE binding properties similar to those found for native Ara h 1 , indicating that the allergenicity of Ara h 1 is heat-stable. We conclude that the allergenicity of Ara h 1 is unaffected by heating, although native Ara h 1 undergoes a significant heat-induced denaturation on a molecular level, indicating that the recognition of conformational epitopes of Ara h 1 by IgE either is not a dominant mechanism or is restricted to parts of the protein that are not sensitive to heat denaturation.
ISSN:	0021-9258 1083-351X