H. Kumagai et al., INFLUENCE OF PHYTATE REMOVAL AND STRUCTURAL MODIFICATION ON THE CALCIUM-BINDING PROPERTIES OF SOYBEAN GLOBULINS, Bioscience, biotechnology, and biochemistry, 62(2), 1998, pp. 341-346
The calcium-binding properties of soybean globulins that have been dea
midated or enzymatically hydrolyzed after the removal of phytate were
physicochemically investigated. The level of calcium was reduced from
0.32% to 0.013% and that of phosphorus was reduced from 1.1% to 0.050%
by treating with cation-and anion-exchange resins. The calcium-bindin
g properties of soybean globulins were described by the Langmuir equat
ion, the maximum amount of bound calcium (N) and the affinity paramete
r for calcium (K) being obtained for each sample. The value of N was d
ecreased by the removal of phytate, while the deamidation caused the v
alue of N to increase. As hydrolysis proceeded, the value of N increas
ed to a degree of hydrolysis of 32%, and then decreased. Based on this
result, there seems to be an optimum molecular weight of hydrolyzed s
oybean globulins for the amount of bound calcium. In addition, the val
ue of K for every soybean globulin sample was much lower than that of
phytic acid, indicating that the globulins had proper calcium-binding
properties for calcium absorption in the small intestine.