Effects of Soybean Saponins on Chymotryptic Hydrolyses of Soybean Proteins

The effects of saponin fraction on chymotryptic hydrolysis of soybean acid precipitated protein and glycinin and β-conglycinin fractions were examined. Endogenous saponin affected the chymotryptic hydrolysis of soybean protein. Further addition of saponin suppressed the hydrolysis of soybean protein fraction. The effect of saponin on chymotryptic hydrolysis of glycinin was greater than on that of β-conglycinin. There were some differences in the effect of saponin on the subunits constituting the soybean globulins. Glycinin acidic polypeptides and β-conglycinin β-subunit became more resistant to chymotryptic hydrolyses by addition of saponin. Changes of CD spectra of glycinin and β-conglycinin by saponin reflected the sensitivity changes of soybean protein against chymotrypsin. Keywords: Soybean saponin; chymotrypsin hydrolysis; glycinin; β-conglycinin