![]() ![]() Ara h 2 was described as the most important peanut allergen, as it was identified as a predictor of clinical reactivity to peanut. Peanut allergens from the Bet v 1, profilin, oleosin, and defensin familiesĪra h 8, a homolog of the major birch pollen allergen Bet v 1, and Ara h 5, a profilin, are mostly involved in pollen-associated food allergy, while the peanut nsLTP Ara h 9 is involved in the so-called nsLTP-syndrome due to the cross-reactivity with their homologs in birch and/or grass pollen or in fruits and seeds, respectively. The cross-reactivity between the 2S albumin Ara h 2 and the cupins Ara h 1 and 3 is based on the presence of short similar structural motifs. Only recently, cross-reactivity between two unrelated protein architectures has been described for the first time. ![]() However, the in vitro-observed IgE cross-reactivity of such panallergens is not always associated with clinical symptoms. Thus, protein evolution explains the occurrence of so-called panallergens - such as the Bet v 1 homologs - in many unrelated allergen sources. Non-specific lipid transfer proteins (nsLTPs) have only been identified in seed plants but are not even present in algae. In contrast, the prolamin superfamily seems to be of a later origin. Like members of the cupin superfamily, Bet v 1-like proteins can be found in all three domains of life including birch pollen and peanut. 2NS9) whose architecture is identical to that of Bet v 1 (PDB 1BV1). Aeropyrum pernix, an archaeon that was isolated from a hydrothermal vent near a Japanese island in 1996, produces the protein APE2225 (PDB accession no. The most important storage proteins of legumes, tree nuts and seeds are members of the cupin superfamily. The typical cupin domain first appeared in extremophile Archaea. Archaea are also the oldest form of life on earth with an estimated age of 3.5 billion years. The cupin and the Bet v 1 architectures can be traced back to the Archaea. Thus proteins that appeared very early in the evolutionary process are distributed much wider than proteins that appeared later on. Protein evolution is linked to the evolution of species. Ĭross-reactivity relies on the presence of conserved antibody-accessible surface structures of proteins and is hence observed in general between members of the same protein family. In a recent study, all known peanut allergen classes were determined to comprise 85 % of the total protein content of peanut while Ara h 1, Ara h 2, and Ara h 3 together accounted for 75 %. The cupin Ara h 1 was determined to contribute 12–16 %, and the 2S albumin Ara h 2 5.9–9.3 % to the total protein content of a peanut. Most of the protein content is made up by seed storage proteins of the cupin or prolamin superfamilies. The total protein content of three of the most commonly used peanut cultivars (Valencia, Virginia, and Spanish) was determined to be between 24 and 29 %. Peanuts contain 44–56 % oil and 22–30 % protein. Peanuts are very rich in nutrients and are one of the basic crops of India, China, the USA and West Africa. The typical peanut seed pod which usually contains two seeds matures buried underground. The peanut is botanically related to beans and peas but not to tree nuts. Peanuts are the seeds of the peanut plant ( Arachis hypogaea) which is a member of the legume family (Fabaceae). This review also addresses the less well-studied cross-reactivity between cupin and prolamin allergens of peanuts and of other plant food sources and the recently discovered cross-reactivity between peanut allergens of unrelated protein families. Molecular cross-reactivity has been described between members of the Bet v 1-like proteins, the non-specific lipid transfer proteins, and the profilins. Clinical observations frequently report an association of peanut allergy with allergies to legumes, tree nuts, seeds, fruits and pollen. Two allergens belong to the cupin and four to the prolamin superfamily, and six are distributed among profilins, Bet v 1-like proteins, oleosins, and defensins. Currently, the IUIS allergen nomenclature subcommittee accepts 12 peanut allergens. This article describes the classification and molecular biology of peanut seed allergens with particular reference to their cross-reactivities. ![]() Peanut seeds are currently widely used as source of human food ingredients in the United States of America and in European countries due to their high quality protein and oil content. ![]()
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