• The Korean Journal of Food And Nutrition
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• v.12 no.2
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• pp.184-190
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• 1999

Soybean protein consists of two major components $\beta$-conglycinin and glycinin which together consti-tute 70% of the total seed storage protein at maturity. $\beta$-Conglycinin is trimeric glycoprotein and for-med by the assembly of various combinations of three subunits $\alpha$,$\alpha$' and $\beta$ which have molecular weig-hts of 69,000, 72,000 and 42,000, respectively. Recently $\beta$-conglycinin was identified as powerful LDL lip-oprotein receptor activation hypercholesterolemia and major allergenic proteins. To investigate these reasons we constructed an expression system of cDNA encoding $\alpha$-subunit of $\beta$-conglycinin in Escherichia coli and purified the expressed protein. The pro-$\beta$-conglycinin synthesized in Escherichia coli BL 21 (DE3)comprised approximately 15% of the total bacterial proteins and the expressed protein are formed sol-uble and trimer such as native protein in Escherichia coli cells. The highly expressed protein was purified to homogeneity by salt precipitation with 20~40 % ammonium sulfate ion-exchange chromatography with Q-sepharose and hydrophobic column chromatography with Butyltoyopearl.

• Food Science and Biotechnology
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• v.14 no.1
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• pp.11-15
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• 2005

Dynamic shear moduli of isolated soy protein solutions upon heating were measured to monitor gelation. Onsets of gelation coincide with onset temperatures of denaturation in glycinin and ${\beta}$-conglycinin solutions, whereas in isolated soy proteins, onset of gelation was above denaturation temperature of ${\beta}$-conglycinin with storage modulus increasing in two steps. The first increase in storage modulus of isolated soy proteins occurred at about $78.5^{\circ}C$, while the second increase started at about $93^{\circ}C$. Gel properties of soy protein gels having different proportions of glycinin and ${\beta}$-conglycinin were measured by compression-decompression test. ${\beta}$-conglycinin was responsible for gel elasticity. Glycinin significantly increased hardness, toughness, and fracturability of gels at high heating temperature near $100^{\circ}C$. Results reveal texture of soy protein gels can be controlled by regulating ratio of glycinin to ${\beta}$-conglycinin and heating temperature.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.2
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• pp.85-94
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• 2002

Antibodies raised against the purified p-subunit of $\beta$-conglycinin were used in immunohistochemical studies to monitor the pattern of $\beta$-conglycinin mobilization in the cotyledons during soybean [Glycine max (L.) Merr.] seed germination. Western blot analysis revealed that the break down of the $\beta$-subunit of $\beta$-conglycinin commenced as early as 2 days after seed imbibition (DAI). Concurrent with the degradation of the $\beta$-subunit of $\beta$-conglycinin, accumulation of 48, 28, and 26 kD proteolytic intermediates was observed from 2 to 6 DAI. Western blot analysis also revealed that the acidic subunit of glycinin was mobilized earlier than the basic subunit. The basic glycinin subunit was subjected to proteolysis within 2 DAI resulting in the appearance of an intermediate product approximately 2 kD smaller than the native basic glycinin subunit. In contrast to the major seed storage proteins, lipoxygenase was subjected to limited proteolysis and was detected even after 8 DAI. The first sign of $\beta$-conglycinin breakdown was observed near the vascular strands and proceeded from the vascular strands towards the epidermis. Protein A-gold localization studies using thin sections of soybean cotyledons and antibodies raised against the $\beta$-subunit of $\beta$-conglycinin revealed intense labeling over protein bodies. A pronounced decrease in the protein A-gold labeling intensity over protein bodies was observed at later stages of seed germination. The protein bodies, which were converted into a large central vacuole by 8 DAI, contained very little 7S protein as evidenced by sparse protein A-gold labeling in the vacuoles.

• Applied Biological Chemistry
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• v.36 no.6
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• pp.547-552
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• 1993

Soybean nuclear extracts and S-100 were prepared to examine the soybean embryo factors which bind to the upstream region of soybean ${\beta}-conglycinin$ ${\alpha}'$ subunit gene. SEF3(soybean embryo factor 3), which is presumed to be a trans-acting factor for the expression of the gene, was detected in gel mobility shift assay using the DNA probe containing two AACCCA hexanucleotides. DNA probe containing CATGCAT or AACACA was used to find any other soybean embryo factor interacting with the upstream region of ${\beta}-Conglycinin$ ${\alpha}'$ subunit gene. It was found that there was no common DNA binding protein detected both in nuclear extracts and S-100. The relative levels of SEF3 binding activity both in nuclear extracts and S-100 of maturing soybean seeds were determined. SEF3 activity of nuclear extracts was first detected around 20 days after pollination and significantly increased around 32 days after pollination.

• Applied Biological Chemistry
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• v.36 no.6
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• pp.553-556
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• 1993

Soybean nuclear extracts were prepared to examine the expression of SEF3 (soybean embryo factors 3), which binds to the upstream region of soybean ${\beta}-conglycinin$ ${\alpha}'$ subunit gene and is presumed to be a trans-acting factor for the expression of the gene. The relative levels of SEF3 binding activity in nuclear extracts of maturing soybean embryos were determined using the SE3 DNA probe containing two AACCCA hexanucleotides for gel mobility shift assay. The SEF3 activity increased in developing embryos from 16 to 32 days after pollination, whereas the mobility of the SE3-SE3-SEF3 complex decreased. The mobility of the complex was increased by the treatment of nuclear extracts with alkaline phosphatese, which could be inhibited by phosphate. Formation of the SE3-SEF3 complex was not affected by the binding buffer pH between 6.8 and 8.5.

• Korean Journal of Plant Resources
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• v.10 no.3
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• pp.221-226
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• 1997

Improvement of seed protein quality might be an essential issus in soybean and would give more profit directly to both farmers and users. This study was carried out to investigate the effects of reduced-S form(s) on seed storage protein components in soybean during seed filling stages. The reduced-S forms during seed fill were sodium thiosulfate, sodium sulfite, sodium sulfide, thioaceteat, $\beta$-mercaptoethanol, thiourea, thiamine-HCI, L-cysteine, L-cystine, and L-methionine. Seed storage protein concentration did not appear to be affected by any reduced-S forms. However, glycinin and $\beta$-conglycinin concentration seemed to be changed greatly by L-methionine. This resulted in the increase in the 11S/7S ratio(3.58). Among the $\beta$-conglycinin, $\beta$-subunit was not accumulated at all. $\alpha$-subunit concentration appeared to be decreased and $\alpha'$-subunit concentration was not altered in comparison with sulfate control. Also, $\beta$-conglycine concentration, especially $\beta$-subunit concentration, tended to be decreased with L-cystine treatment, resulting in an increase in the 11S/7S ratio(1.83). The glycinin concentration tended to be increased at the expense of the decrease in the $\beta$-conglycinin concentration. Therefore, it is suggested that enhancing soybean protein quality would be achieved by improving metabolic pathways of S assimilation in soybean plants during seed filling period under sulfate-sufficient condition.

• The Korean Journal of Food And Nutrition
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• v.9 no.4
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• pp.404-408
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• 1996

One of the major objectives of the food industry is the enrichment of the functional properties and nutritional value of soybean protein. To attain this goal, an expression system of cDNA encoding native and protein-engineered soybean proteins in a microorganism must be developed and the function then ability of self-assembly and the functionalities of the expressed proteins should be evaluated before the modified genes are transfered to soybean plants. The pro-$\beta$-conglycinin synthesized in E. coli BL21(DE3) comprised approximately 20% of the total bacterial proteins and the expressed protein are formed soluble and trimer such as native protein in E. coli cells. The highly expressed protein was purified to homogeneity by salt precipitation with 20~40$ Ammonium sulfate ion-exchange chromatography with Q-Sepharose and hydrophobic column chromatography with Butyltoyopearl. Therefore, we concluded that the high-level expression system of $\beta$-conglycinin cDNA was established and a relatively simple and rapid method for purifying pro-$\beta$-conglicinin was also developed.

• Applied Biological Chemistry
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• v.38 no.1
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• pp.63-66
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• 1995

Soybean nuclear extracts were prepared to detect SEF3(soybean embryo factor 3), which is presumed to be a trans-acting factor for the expression of the soybean ${\beta}-conglycinin\;{\alpha}'$ subunit gene. To increase the specific activity of DNA probe during labeling with $[{\alpha}-^{32}P]$dATP, dATP was added to a final concentration of 1.1 mM during the chase reaction. It results in approximately four-fold increase of specific activity of the DNA probe. Effects of several modifications in preparation of soybean nuclear extracts were examined. It was found that glycerol is effective to stabilize SEF3 during the preparation of nuclear extracts and polyethylenimine could be used to increase the specific activity of SEF3 in nuclear extracts.

• Food Science and Biotechnology
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• v.15 no.1
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• pp.128-132
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• 2006

This study was undertaken to investigate the effect of peptic and chymotryptic hydrolyses of 7S globulin, the major allergen of soybean protein, on its allergenicity, as measured by enzyme linked immunosorbent assay (ELISA), and to identify the allergenic hydrolyzed fragments of 7S globulin using SDS-PAGE. When 7S globulin was hydrolyzed by pepsin, the allergenicity was reduced by over 50%. However, the allergenicity of 7S globulin reduced by peptic hydrolysis was recovered in the sera from 5 out of 10 patients following sequential chymotryptic hydrolysis. Two fragments, with molecular weights 20-25 and 13-16 kDa, among the hydrolysate of 7S globulin by sequential pepsin and chymotrypsin showed reactivity with sera from 10 soybean-allergenic patients. As a result of the theoretical hydrolyses of ${\beta}$-conglycinin, which is a major protein of 7S globulin, it is suggested that the 20-25 kDa fragments were the fragments of the ${\alpha}$-subunit of ${\beta}$'-conglycinin and that the 10-16 kDa fragments were from the ${\alpha}$'-subunit.

• Journal of agriculture & life science
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• v.43 no.5
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• pp.39-42
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• 2009

Soybean is an important sources of plant proteins for human and animal nutrition. The use of soybean proteins has been expanded in the food industry due to their excellent nutritional benefits. But, Soybeans contain allergenic proteins that cause allergies to sensitive individuals. ${\beta}$-conglycinin(7S globulin) and glycinin(11S globulin) are the major components of storage protein in soybean. ${\beta}$-conglycinin consists of three subunits, ${\alpha}^{\prime}$, ${\alpha}$, ${\beta}$ and exhibits poorer nutritional and food processing properties than glycinin. There is a great deal of interest in the development of soybean lines with reduced amounts of ${\beta}$-conglycinin. The objective of this study was to determine the inheritance of ${\alpha}^{\prime}$-subunit protein in 7S globulin. F2 population was developed from the cross of "Jinpumkong2ho"(${\alpha}^{\prime}$-subunit presence) and PI506876(${\alpha}^{\prime}$-subunit absence) parent. Total 98 of F2 seeds were obtained and analyzed for the segregation of ${\alpha}^{\prime}$-subunit protein by SDS-PAGE. Among 98 F2 seeds, 70 F2 seeds showed ${\alpha}^{\prime}$-subunit protein and 28 F2 seeds did not show ${\alpha}^{\prime}$-subunit protein. The segregation ratios of 3 : 1 for presence and absence of ${\alpha}^{\prime}$-subunit protein were observed(${\chi}^2=0.667$, P=0.414). These data indicate that presence and absence of ${\alpha}^{\prime}$-subunit protein is controlled by a single major gene and might be useful for strain selection of 7S protein reduced soybean.