Determination of Pepsin-Susceptible and Pepsin-Resistant Epitopes in Native and Heat-Treated Peanut Allergen Ara h 1

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• 作者：Evelien L. van Boxtel ; Stef J. Koppelman ; Lambertus A. M. van den Broek ; Harry Gruppen
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2008
• 出版时间：March 26, 2008
• 年：2008
• 卷：56
• 期：6
• 页码：2223 - 2230
• 全文大小：666K
• 年卷期：v.56,no.6(March 26, 2008)
• ISSN：1520-5118

文摘

This study was aimed at the determination of the pepsin-susceptible and pepsin-resistant epitopes in native and heat-treated Ara h 1, a major allergen from peanuts. Both the oligomeric structure and the trimeric structure of the allergen were investigated. Under the in vitro conditions applied, oligomeric Ara h 1, either unheated or preheated, was hydrolyzed by pepsin at a lower rate than trimeric Ara h 1. Peptides with relatively high molecular masses were shown to be able to bind IgE, whereas peptides with lower molecular masses (<2 kDa) did not. In these latter fractions, fragments of 15 previously published epitopes of mature Ara h 1 were identified. As a result, these epitopes are not likely responsible for the induction of systemic food allergic reactions to peanuts. Using sequential chymotrypsin digestion, the pepsin-resistant IgE-binding peptides were deduced to contain the previously identified intact epitopes EDWRRPSHQQ (amino acids 50–59) and PRKIRPEG (amino acids 60–67). The presence of four additional earlier published intact epitopes (covering amino acids 6–13, 14–21, 24–31, and 40–47) on the pepsin-resistant peptides could be neither deduced nor ruled out. The two deduced and four possible pepsin-resistant epitopes are all situated in the N-terminal part of Ara h 1, which does not show homology with other vicilin proteins. Consequently, this unique N-terminal part of Ara h 1 is proposed to be responsible for the allergen’s ability to induce systemic allergic reactions.