title: All three subunits of soybean beta-conglycinin are potential food allergens.
abstract: Soybeans are recognized as one of the "big 8" food allergens. IgE antibodies from soybean-sensitive patients recognize more than 15 soybean proteins. Among these proteins only the alpha-subunit of beta-conglycinin, but not the highly homologous alpha'- and beta-subunits, has been shown to be a major allergenic protein. The objective of this study was to examine if the alpha'- and beta-subunits of beta-conglycinin can also serve as potential allergens. Immunoblot analysis using sera collected from soybean-allergic patients revealed the presence of IgE antibodies that recognized several soy proteins including 72, 70, 52, 34, and 21 kDa proteins. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF) analysis of trypsin-digested 72, 70, and 52 kDa proteins indicated that these proteins were the alpha'-, alpha-, and beta-subunits of beta-conglycinin, respectively. Additionally, purified alpha'-, alpha-, and beta-subunits of beta-conglycinin were recognized by IgE antibodies present in the soybean-allergic patients. The IgE reactivity to the beta-subunit of beta-conglycinin was not abolished when this glycoprotein was either deglycosylated using glycosidases or expressed as a recombinant protein in Escherichia coli . The results suggest that in addition to the previously recognized alpha-subunit of beta-conglycinin, the alpha'- and beta-subunits of beta-conglycinin also are potential food allergens.
authors.affiliation: U.S. Department of Agriculture, Division of Plant Sciences, Plant Genetics Research Unit, Agricultural Research Service, University of Missouri, Columbia, Missouri 65211, USA. Hari.Krishnan@ARS.USDA.GOV
authors.forename: Hari B
authors.initials: HB
authors.lastname: Krishnan
authors.forename: Won-Seok
authors.initials: WS
authors.lastname: Kim
authors.forename: Sungchan
authors.initials: S
authors.lastname: Jang
authors.forename: Monty S
authors.initials: MS
authors.lastname: Kerley
mesh_terms: D000328:Adult; D000485:Allergens / Q000737:chemistry / Q000276:immunology*; D000595:Amino Acid Sequence; D052179:Antigens, Plant; D005512:Food Hypersensitivity / Q000276:immunology*; D005916:Globulins / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D015151:Immunoblotting; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D008969:Molecular Sequence Data; D021122:Protein Subunits / Q000276:immunology*; D055314:Seed Storage Proteins / Q000737:chemistry / Q000276:immunology*; D012639:Seeds / Q000737:chemistry / Q000276:immunology; D030262:Soybean Proteins / Q000737:chemistry / Q000276:immunology*; D013025:Glycine max / Q000737:chemistry* / Q000276:immunology
chemical_list: D000485:Allergens; D052179:Antigens, Plant; D005916:Globulins; D021122:Protein Subunits; D055314:Seed Storage Proteins; D030262:Soybean Proteins; C013894:beta-conglycinin protein, Glycine max; D007073:Immunoglobulin E