Glycinin, one of the predominant storage proteins in soybeans, was examined as to whether it could be used as a calcium-binding mediator after chemical phosphorylation and enzymatic hydrolysis. Glycinin is composed of six subunits. One of the proglycinin subunits (A1aB1b) was overexpressed in E. coli to obtain nonphosphorylated proteins with homogeneity. To investigate the enhanced calcium-binding properties of the phosphopeptides, the proglycinin was purified, phosphorylated, and hydrolyzed with trypsin. The proglycinin expressed in E. coli was purified by ammonium sulfate precipitation, ion-exchange chromatography, and cryoprecipitation. Chemical phosphorylation by sodium trimetaphosphate was performed to obtain phosphorylated proglycinin. After the phosphorylation, one-dimensional isoelectric focusing gel electroanalysis confirmed the phosphorylation of the proglycinin. The phosphorylated peptides were then hydrolyzed with trypsin, followed by a binding reaction with calcium chloride. The calcium-bound phosphopeptides were finally separated using immobilized metal (Ca2+) chromatography. Consequently, a limited tryptic hydrolysate of the isolated phosphopeptides exhibited an enhanced calcium-binding ability, suggesting the potential of glycinin phosphopeptides as a calcium-binding mediator with greater availability.
|Number of pages||5|
|Journal||Journal of microbiology and biotechnology|
|Publication status||Published - 2004 Jun|
- 1-D IEF gel
ASJC Scopus subject areas
- Applied Microbiology and Biotechnology