Both solubility tests and reference data proved that commercially available soy protein isolate (SPI) had low solubility in pure water.As an alternative

guanidine hydroxyl chloride (GuHCl) and dithiothreitol (DTT) were used to treat SPI during the dissolution process.After dialysis of GuHCl and DTT

an SPI aqueous solution was obtained.Solubility tests showed this SPI aqueous solution had a relatively high concentration (6 times larger as that directly dissolved in pure water)

and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that such an SPI solution did not suffer the degradation of the protein subunits.In addition

through a simple treatment of GuHCl and dialysis process

a 7S-rich solution and an 11S-rich sediment were obtained

so that the two major components of SPI were primarily separated.SDS-PAGE gave the major evidence of the separation

and the possible mechanism of the separation was discussed.It was a relative simple method with high productivity

though the separation efficiency was lower than that of the chromatography method.The paper provides new insights into the role of disulfide bonds that play in stabilizing the structure of SPI

especially that of the component 11S