A Novel Enzyme-Linked Immunosorbent Assay for Quantification of Soybean .BETA.-Conglycinin, a Major Soybean Storage Protein, in Soybean and Soybean Food Products

Soybean (Glycine max L.) storage proteins are composed of two major components, beta-conglycinin and glycinin, corresponding to 7S and 11S globulins, respectively. Recently, soybean beta-conglycinin (7S globulin) has been reported to show beneficial functions in animals and human. To date, there is no method for the precise quantification of soybean beta-conglycinin in processed food products or soybean seeds. We report here a novel method for this purpose. At first, antibodies specifically reactive to the subunits of beta-conglycinin were prepared. And then, a direct enzyme-linked immunosorbent assay (ELISA) for the quantification of soybean beta-conglycinin in processed foods and seeds was developed. In this assay, the sample was treated with sodium dodecyl sulfate sample buffer followed by dilution with phosphate-buffered saline. The diluted samples were poured and coated onto an ELISA plate and reacted with rabbit anti-beta-conglycinin antibody and peroxidase-labeled anti-rabbit IgG. Finally, the bound peroxidase-labeled antibody was detected by colorimetric reaction. By using this system, it has been possible to measure soybean beta-conglycinin concentrations in several processed food products. In addition, this simple quantification ELISA system was demonstrated to be adaptable for the quantification of beta-conglycinin contents of various soybean cultivars.