This study was carried out to know the variation of soybean seed proteins, 11S and 7S globulins, and their amino acid compositions among different colored soybean varieties, 'Danbaegkong' (yellow), 'Pureunkong' (green) 'Jinyulkong' (brown), and 'Geoumjeongkong l' (black). Soybean seed proteins showed a wide range in molecular size, but the electrophoresis patterns of total seed protein subunits showed a similarity among different colored soybean varieties. Amino acid compositions of total seed proteins were similar for all soybean varieties tested. However, soybean varieties showed low composition rates in sulfur containing amino acids. The composition rates of cysteine and methionine in the 11S globulins were higher than those of total seed proteins and 7S globulins. Glutamic acid and glycine were higher in the 11S and 7S globulins than those of total seed proteins. However, the levels of methionine and phenylalanine are high in the 11S globulins, but those of valine and lysin are slightly lower than the 7S globulins. By using HPLC, we tried to analyse the soybean seed proteins. The 11S globulin was composed of 10 major peaks whereas the 7S globulin was composed of 4 major peaks. The composition rates of 11S related proteins have a tendency to increasing during the maturing whereas those of 7S related proteins have a tendency to decreasing. Composition rates of each peaks among different colored soybean varieties suggested that soybean seed proteins are varied, although they showed similarity in the electrophoresis patterns, and understanding of this characteristics is important for the utilization of soybeans.

Soybean is an important crop because its seed has very high protein relative to others. The quality of soy protein is limited by the concentration of the sulfur-containing amino acids in the amino acid profile. Among the supply of various forms of 0.4mM sulfur as S nutrition during seed fill. only 0.4mM L-methionine can inhibit β-subunit synthesis completely and produce the highest glycinin-containing seeds. Compared to 0.4mM sulfate control, seeds supplied by 0.4mM L-methionine have lower α-, no β-subunit, and highly increased glycinin without altering total protein concentration. Supply of 0.2mM cystine (0.4mM S) did not affect the accumulative pattern of seed storage protein (SSP) subunits. In the supply of L-methionine, 0.2mM treatment showed higher glycinin in seeds but 0.05mM resulted in lower glycinin than tile sulfate control. The relative abundance of α`-subunit was not altered by any N or S nutrition. Under 5mM nitrogen, protein concentration was increased about 3-5% by substituting ammonia for nitrate during seed fill independent of nutrition. The increase resulted in the only increase of 7S protein, mainly β-subunit. Our data suggest that the regulatory system of SSP genes responds to the balance between N and S assimilates supplied from mother plant. and controls the di fferential synthesis of their subunits for the maximum protein accumulation in developing soybean seed.