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Soybean protein allergens

Ping Xiang, University of Nebraska - Lincoln


Soybean is an important source of human allergies, and several soybean proteins have been identified as food allergens. An important characteristic of these allergens is their ability to bind to IgE in the sera of soybean allergic individuals. In this thesis, three soybean allergens, namely, glycinin G2 protein acidic chain (G2a), Gly m Bd 28K, and P39, a novel allergen first identified in lecithin, were studied. ^ G2a is an important soybean allergen and is a major storage protein in soybean seeds. Epitope mapping of this protein previously identified a major IgE binding site between residues S219-N233. Gly m Bd 28K is another dominant soybean allergen. Most of the previous work was limited to the N-terminal 240 residues of this protein, whereas in this my work, the full length Gly m Bd 28K polypeptide consisting of 452 residues was studied. Interestingly, an immunodominant IgE-binding epitope was identified in the C-terminal region, between residues 5256-A270. Interestingly, both G2a and Gly m Bd 28K belong to the cupin superfamily of proteins, which contain many food allergens. The epitopes identified on both of the soybean allergens may represent conserved IgE binding sites, since other allergens of the cupin family of proteins have IgE-binding epitopes identified in or adjacent to similar regions of the molecules. These results suggest that structural factors might play an important role in the allergenicity of these proteins. ^ P39 was identified as a novel IgE binding protein from soybean lecithin. It is a low abundant protein and is encoded by a multigene family in soybeans and several other plants. P39 and homologs belong to a family of plant proteins of unknown function. P39 is apparently seed specific and increases in amounts during seed maturation, and is slowly degraded during germination. Although, the protein was enriched in oil body preparations from soybean seeds, it is most likely to be localized in the protein storage vacuoles. ^

Subject Area

Chemistry, Biochemistry

Recommended Citation

Xiang, Ping, "Soybean protein allergens" (2003). ETD collection for University of Nebraska - Lincoln. AAI3092608.