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Allergen Ara h 1 occurs in peanuts as a large oligomer rather than as a trimer

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Author: Boxtel, E.L. van · Beers, M.M.C. van · Koppelman, S.J. · Broek, L.A.M. van den · Gruppen, H.
Type:article
Date:2006
Institution: TNO Kwaliteit van Leven
Source:Journal of Agricultural and Food Chemistry, 19, 54, 7180-7186
Identifier: 239482
doi: doi:10.1021/jf061433+
Keywords: Nutrition · Food technology · Ara h 1 · Food allergen · Peanut · Protein structure · allergen · ammonium sulfate · Ara h 1 protein, Arachis hypogaea · glycoprotein · vegetable protein · article · chemistry · gel chromatography · osmolarity · peanut · plant seed · polyacrylamide gel electrophoresis · precipitation · protein quaternary structure · Allergens · Ammonium Sulfate · Arachis hypogaea · Chromatography, Gel · Electrophoresis, Polyacrylamide Gel · Glycoproteins · Osmolar Concentration · Plant Proteins · Precipitation · Protein Structure, Quaternary · Seeds · Ara · Arachis hypogaea

Abstract

Ara h 1, a major peanut allergen, is known as a stable trimeric protein. Nevertheless, upon purification of native Ara h 1 from peanuts using only size exclusion chromatography, the allergen appeared to exist in an oligomeric structure, rather than as a trimeric structure. The oligomeric structure was independent of the salt concentration applied. Subjecting the allergen to anion exchange chromatography induced the allergen to dissociate into trimers. Ammonium sulfate precipitation did not bring about any structural changes, whereas exposing the allergen to hydrophobic interaction chromatography caused it to partly dissociate into trimers, with increasing amounts of trimers at higher ionic strengths. The (partial) dissociation into trimers led to a change in the tertiary structure of the monomeric subunits of the allergen, with the monomers in Ara h 1 oligomers having a more compact tertiary structure compared with the monomers in Ara h 1 trimers. As structural characteristics are important for a protein's allergenicity, this finding may imply a different allergenicity for Ara h 1 than previously described. © 2006 American Chemical Society.