Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 8, 2002
Publication Date: September 24, 2002
Citation: Brandon, D.L., Friedman, M. 2002. Immunoassays of soy proteins. Journal of Agricultural and Food Chemistry. 50(22):6635-6642. Technical Abstract: Proteins of soybeans (Glycine max) are widely used in animal and human nutrition. About 6% of soybean proteins are classified as inhibitors of trypsin and chymotrypsin. The two major classes of inhibitors are the Kunitz trypsin inhibitor (KTI), which inhibits trypsin and the Bowman-Birk inhibitor (BBI), which inhibits both trypsin and chymotrypsin. These inhibitors can impair nutritional quality and safety of soy-based diets. On the other hand, several studies suggest that BBI can also function as anti-carcinogen, possibly through interaction with a cellular serine protease. These considerations suggest that to improve both human and animal nutrition, as well as to provide foods with specific human health benefits, a need exists to develop soybean lines with both low and high BBI content. To provide analytical methods which would help address this need, we developed antibodies which bind to KTI and BBI and enzyme-linked immunosorbent assays (ELISAs), which utilize these antibodies. The ELISAs are highly specific and were used to analyze active inhibitors in the presence of denatured forms in extracts of soybean seeds and in processed soy foods. They were also used to screen the genus Glycine for soybean lines lacking BBI. BBI nulls were found in several wild perennial species. Additional immunochemical methods and enzymatic assays for trypsin and chymotrypsin confirmed the absence of BBI. It should therefore be possible to develop new soybean lines lacking BBI for use in animal and human nutrition and high in BBI for use in health foods. Immunoassays of soybean proteins can be used in plant science, nutrition and food science, and in studies of food allergy and cancer chemoprevention.