Definition of functional and antibody-binding sites on Kunitz soybean trypsin inhibitor isoforms using monoclonal antibodies

Brandon, David L.; Bates, Anne H.

doi:10.1021/jf00084a053

Cited by 13 publications

(5 citation statements)

References 18 publications

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“…General Aspects. The following discussion on the development and applications of enzyme-linked immunosorbent assays (ELISA) is based largely on our studies ( − ). Trypsin inhibitors constitute ∼6% of the protein of soybeans.…”

Section: Immunoassays Of Kunitz and Bowman−birk Inhibitors Of Digesti...mentioning

confidence: 99%

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Nutritional and Health Benefits of Soy Proteins

Friedman

Brandon

2001

J. Agric. Food Chem.

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767

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Soy protein is a major component of the diet of food-producing animals and is increasingly important in the human diet. However, soy protein is not an ideal protein because it is deficient in the essential amino acid methionine. Methionine supplementation benefits soy infant formulas, but apparently not food intended for adults with an adequate nitrogen intake. Soy protein content of another essential amino acid, lysine, although higher than that of wheat proteins, is still lower than that of the milk protein casein. Adverse nutritional and other effects following consumption of raw soybean meal have been attributed to the presence of endogenous inhibitors of digestive enzymes and lectins and to poor digestibility. To improve the nutritional quality of soy foods, inhibitors and lectins are generally inactivated by heat treatment or eliminated by fractionation during food processing. Although lectins are heat-labile, the inhibitors are more heat-stable than the lectins. Most commercially heated meals retain up to 20% of the Bowman-Birk (BBI) inhibitor of chymotrypsin and trypsin and the Kunitz inhibitor of trypsin (KTI). To enhance the value of soybeans in human nutrition and health, a better understanding is needed of the factors that impact the nutrition and health-promoting aspects of soy proteins. This paper discusses the composition in relation to properties of soy proteins. Also described are possible beneficial and adverse effects of soy-containing diets. The former include soy-induced lowering of cholesterol, anticarcinogenic effects of BBI, and protective effects against obesity, diabetes, irritants of the digestive tract, bone, and kidney diseases, whereas the latter include poor digestibility and allergy to soy proteins. Approaches to reduce the concentration of soybean inhibitors by rearrangement of protein disulfide bonds, immunoassays of inhibitors in processed soy foods and soybean germplasm, the roles of phytoestrogenic isoflavones and lectins, and research needs in all of these areas are also discussed. This integrated overview of the widely scattered literature emphasizes general concepts based on our own studies as well as recent studies by others. It is intended to stimulate interest in further research to optimize beneficial effects of soy proteins. The payoff will be healthier humans and improved animal feeds.

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Section: Immunoassays Of Kunitz and Bowman−birk Inhibitors Of Digesti...mentioning

confidence: 99%

“…(C) ELISA of soy meals from soybean lines expressing each isoform of KTI. (D) Correlation of enzyme inhibitory activity and ELISA of heat-treated KTI ( , ). …”

Section: Immunoassays Of Kunitz and Bowman−birk Inhibitors Of Digesti...mentioning

confidence: 99%

Nutritional and Health Benefits of Soy Proteins

Friedman

Brandon

2001

J. Agric. Food Chem.

Self Cite

767

530

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“…It should be noted that these authors also studied the distribution of protease inhibitors in these washings, exploiting the ability of their rabbit antibodies to bind to inhibitors even when complexed with proteases. In our studies using monoclonal antibodies, we also had found that some antibodies can bind KTI or BBI even in complexes with proteases ( , ). It can be expected that the specificity of monoclonal antibodies for SBA and the enhanced sensitivity of immunochemical methods compared to agglutination techniques will help answer remaining questions about the distribution and function of lectins in legume tissues.…”

Section: Immunochemical Studies Of Soybean Lectinsmentioning

confidence: 84%

“…Antibody 171 binds equally to the different isoforms, as illustrated by nearly identical assay curves. Antibody 180 binds better to isoform b than to isoform a but does not bind isoform c. The isoform specificity of antibody 180 demonstrated with purified KTI preparations was also observed using soymeal prepared from soybeans expressing each of the isoforms (22). Antibody 180 binds to epitope III, which is labile to mild heat treatment and produces an assay that correlates with enzymatic estimation of trypsin inhibition over a wide range of activities (Figure 4).…”

Section: Structure and Immunochemistry Of The Kunitz Soybean Trypsin ...mentioning

confidence: 87%

“…Monoclonal antibodies (MAbs) were developed and specificities were determined by ELISA, using one of several formats ( − ): (a) direct binding of antibody to solid-phase KTI; (b) competitive ELISA format I, in which liquid-phase sample inhibits binding of antibody to the solid-phase KTI; (c) competitive ELISA format II, in which liquid-phase sample and enzyme-labeled KTI compete for solid-phase antibody-binding sites; and (d) epitope mapping, in which labeled and unlabeled monoclonal antibodies compete for solid-phase KTI epitopes. Studies were performed using purified KTI isoforms as well as isolines of soybeans that express only a single isoform.…”

Section: Structure and Immunochemistry Of The Kunitz Soybean Trypsin ...mentioning

confidence: 99%

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Immunoassays of Soy Proteins

Brandon

Friedman

2002

J. Agric. Food Chem.

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Proteins of soybeans (Glycine max) are widely used in animal and human nutrition. In addition to the bulk of the seed storage proteins, which are classified as albumins and globulins, approximately 6% of soybean proteins are classified as inhibitors of trypsin and chymotrypsin and approximately 0.5% are sugar-binding lectins. The two major classes of inhibitors are the Kunitz trypsin inhibitor, which inhibits trypsin, and the Bowman-Birk inhibitor (BBI), which inhibits both trypsin and chymotrypsin. Unless removed or inactivated, these inhibitors and lectins can impair the nutritional quality and safety of soy-based diets. On the other hand, several studies suggest that BBI can also function as an anticarcinogen, possibly through interaction with a cellular serine protease. Good-quality soybean proteins contribute to the nutritional value of many specialty foods including infant soy formulas and milk replacers for calves, and provide texture to many processed foods. However, they may also induce occasional allergic responses in humans. This paper outlines immunoassays developed to analyze for soy proteins in different soybean lines, in processed foods, and in nonsoy foods fortified with soy proteins. An assessment of the current status of immunoassays, especially of enzyme-linked immunosorbent assays for soybean inhibitors of digestive enzymes, soy globulins, and soy lectins, demonstrates the usefulness of these methods in plant and food sciences and in medicine.

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