Protein of soybean

Nagao, R.T., Czamecka, E., Gurley, W.B., Schoffl, F. Key, J.L. (1985). Genes for low-molecular-weight heat shock proteins of soybeans Sequence analysis of a multigene family. Molecular and Cellular Biology, 5, 3417-28. 

Schoffl, F. Key, J.L. (1982). An analysis of mRNA s for a group of heat shock proteins of soybean using cloned cDNA s. Journal of Molecular and Applied Genetics, 1, 301-14. 

Thanh VH and Shibasaki K. Major proteins of soybean seeds. A straightforward fractionation and their characterization. J. Agric. Food Chem. 1976 24, 4(6) 1117-1121. 

Naeve and Orf (2006) conducted a soybean measurement survey of 1593 samples for the American Soybean Association and found that in 2006 average protein of soybeans grown in the United States was 34.51% (13% moisture basis) and average oil was 19.17% (13% moisture basis) (Table 6.5). 

Scott, M.P. R. Jung K. Muntz N.C. Nielsen. A protease responsible for post-translational cleavage of a conserved Asn-Gly linkage in glycinin, the major seed storage protein of soybean. Proc. National Acad. Sci. 1992, 89, 658-662. 

LaFayette, P.R., R.T. Nagao, K. O Grady, E. Vierling, and J.L. Key. 1996. Molecular characterization of cDNAs encoding low-molecular-weight heat shock proteins of soybean. Plant Mol. Biol. 30 159-169. 

Burks AW, Brooks JR, Sampson HA. Allergenicity of major component proteins of soybean determined by enz5mie linked immunosorbent assay (ELISA) and im-munoblotting in children with atopic dermatitis and positive soy challenges. J Allergy Clin Immunol 1988 81 1135-1142. 

Plant proteins from single sources, such as soybean meal, may be abundant in specific amino acids that are deficient in some cereal grains. Thus a combination of soybean meal and com with theh amino acid symbiosis may provide an exceUent amino acid profile for dogs. Plant protein mixtures alone do not meet the amino acid needs for cats, because taurine [107-35-7] is not generaUy present in plant proteins. 

Fig. 2. Ultracentrifugal pattern for the water-extractable proteins of defatted soybean meal in pH 7.6, 0.5 ionic strength buffer. Numbers above peaks are approximate sedimentation coefficients in Svedberg units, S. Molecular weight ranges for the fractions are 2S, 8,000—50,000 7S, 100,000—180,000 IIS, 300,000—350,000 and 15S, 600,000—700,000 (9). The 15S fraction is a dimer of the IIS protein (10).

Fig. 3. Sodium dodecyl sulfate—polyacrylamide gel electrophoretic pattern for molecular weight standards (lane 1) water-extractable proteins of defatted soybean meal (lane 2) purified IIS (glycinin) (lane 3) and purified 7S (P-conglycinin) (lane 4) where the numbers represent mol wt x 10. The gel was mn in the presence of 2-mercaptoethanol, resulting in the cleavage of the disulfide bond linking the acidic (A bands) and basic (B bands) polypeptides of the...

A metric ton of soybeans yields 181 kg of cmde oil, 794 kg of 44% protein meal (hulls present), or 722 kg of 48% protein meal (hulls removed) plus 72 kg of hulls. Shrinkage is 25 kg. 

Free substitution of protein meals ia feeds is much more restricted than interchange of oils ia foods. Because of a good balance of essential amino acids, soybean meal is an indispensable ingredient for efficient feeding of nonmminants, eg, poultry and swine. Soybeans provide ca 60% of the world s protein meals, including fish meal (Table 14). Of the 30.0 x 10 t of soybean meal produced in the United States in 1994—1995, 24.2 x 10 t was used domestically, primarily in feeds, and 5.7 x 10 t was exported (50). In the United States, poultry consume the largest share of soybean meal, followed by swine. Lesser amounts are fed to beef and dairy catde. Soybean meal is a principal ingredient in many pet foods (see Feeds and feed additives). 

Pea.nuts, The proteins of peanuts are low in lysine, threonine, cystine plus methionine, and tryptophan when compared to the amino acid requirements for children but meet the requirements for adults (see Table 3). Peanut flour can be used to increase the nutritive value of cereals such as cornmeal but further improvement is noted by the addition of lysine (71). The trypsin inhibitor content of raw peanuts is about one-fifth that of raw soybeans, but this concentration is sufficient to cause hypertrophy (enlargement) of the pancreas in rats. The inhibitors of peanuts are largely inactivated by moist heat treatment (48). As for cottonseed, peanuts are prone to contamination by aflatoxin. FDA regulations limit aflatoxin levels of peanuts and meals to 100 ppb for breeding beef catde, breeding swine, or poultry 200 ppb for finishing swine 300 ppb for finishing beef catde 20 ppb for immature animals and dairy animals and 20 ppb for humans. 

Table 17. Compositions of Soybean Protein Products and Their Uses, wt %...

Use of some oilseed proteins in foods is limited by flavor, color, and flatus effects. Raw soybeans, for example, taste grassy, beany, and bitter. Even after processing, residues of these flavors may limit the amounts of soybean proteins that can be added to a given food (87). The use of cottonseed and sunflower seed flours is restricted by the color imparted by gossypol and phenoHc acids, respectively. Flatus production by defatted soy flours has been attributed to raffinose and stachyose, which are removed by processing the flours into concentrates and isolates (88). 

Soybean Protein Isolates. Soybean protein isolates, having a protein content of >90 wt%, are the only vegetable proteins that are widely used in imitation dairy products (1). Most isolates are derived from isoelectric precipitation, so that the soybean protein isolates have properties that are similar to those of casein. They are insoluble at thek isoelectric point, have a relatively high proportion of hydrophobic amino acid residues, and are calcium-sensitive. They differ from casein in that they are heat-denaturable and thus heat-labile. The proteins have relatively good nutritional properties and have been increasingly used as a principal source of protein. A main deterrent to use has been the beany flavor associated with the product. Use is expected to increase in part because of lower cost as compared to caseinates. There has been much research to develop improved soybean protein isolates. 

Soybean-based ice cream products, technologically feasible, are generally not in use because of flavor problems. An acceptable ice cream has been made by replacing 50% of the nonfat milk soHds with a dried soy protein isolate made up of cheese whey (21). Chocolate flavor has been widely used to mask the flavor of soybean proteins in ice cream (see Flavors and spices). 

The rapid repression of pre-existing protein synthesis caused by anaerobic treatment is correlated with a near complete dissociation of polysomes in primary roots of soybeans (Lin Key, 1967) and maize (E.S. Dennis and A.J. Pryor, personal communication). This does not result from degradation of aerobic mRNAs, because the mRNAs encoding the pre-existing proteins remain translatable in an in vitro system at least five hours after anaerobic treatment is initiated (Sachs et al., 1980). This is in agreement... 

HARRISON E, ADJEi A, AMEHO c, YAMAMOTO s and KONO s (1998) The effect of soybean protein on bone loss in a rat model of postmenopausal osteoporosis. JNutr Sci Vitaminol 44, 257-68. 

We therefore developed an ELISA for the detection of soybean protein in processed foods using polyclonal antibodies raised against p34 as a soybean marker protein and using a specific extraction buffer (Morishita et ah, 2008). The p34 protein, originally characterized as an oil... 

Morishita, N., Kamiya, K., Matsumoto, T., Sakai, S., Teshima, R., Urisu, A., Moriyama, T., Ogawa, T., Akiyama, H., and Morimatsu, F. (2008). A reliable enzyme-linked immunosorbent assay for determination of soybean proteins in processed foods. /. Agric. Food Chem. 56, 6818-6824. 

The following suggested protocol was developed by Barb Olson at Thermo Fisher for the labeling of soybean trypsin inhibitor (STI) with its subsequent complexation with trypsin. Modifications to this procedure may have to be done for other proteins. 

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