BIOCHEMICAL-CHARACTERIZATION OF SOYBEAN PROTEIN CONSISTING OF DIFFERENT SUBUNITS OF GLYCININ

Soybean isogenic lines having different glycinin subunit compositions are now being bred. To compare the characteristics of the genetically improved soybean proteins, total protein and purified glycinin protein s were investigated in this study. The absence of subunit(s) resulted in marked changes in the proportion of glycinin to beta-conglycinin. W hen the pH of the total protein and glycinin solution was changed and NaCl was added to the solution, glycinin consisting of only group I su bunits and beta-conglycinin are highly soluble compared to the A(5)A(4 )B(3) or A(3)B(4) subunit at a NaCl concentration lower than 0.05 M at pH 5.5. Ultracentrifuge analysis showed that the glycinin containing all subunits was able to assemble to form the 11S structure. That cons isting of group I subunits formed a uniform 7S structure. Decreasing g lycinin/beta-conglycinin ratios and structural changes caused by a lac k of glycinin subunit(s) are thus expected to influence the food-proce ssing properties of soybeans.