Gelation of Urea Denatured Soybean Acid Precipitated Protein

Abstract

Acid precipitated soybean protein was denatured with 8M urea and dialyzed against 0.05M Tris-HCl buffer(pH 8.0). The protein solution became a high viscous solution or a gel by dialysis against the 12-fold excess of the buffer, but dialysis against the 40 or above fold excess of the buffer did not result in gelation. The viscosity of the obtained solution highly decreased by the addition of 2-mercaptoethanol. This suggests the large contribution of disulfide bridges to the gel structure. A part of these bridges was formed during the urea denaturation. However, it was not clear that only disu1fide bridges were responsible for the gel structure. Also, SDS polyacrylamide gel electrophoresis showed that glycinin mainly contributed to the disulfide bridge formation.