Characterization of Conformational Structures of Plant Proteins in Solutions

In this work, conformational structures of glycinin and beta-conglycinin were characterized in aqueous solvents containing different urea concentrations and pH values in order to find industrially processable denatured conformations. The results revealed that both proteins possess thermoset behaviors without melting points. Dynamic light scattering and circular dichroism of the solutions were measured. Structural dissociation of the proteins into subunits occurred at high concentrations of urea in protein solutions under either very acidic or very alkaline conditions. Hydrodynamic radii of the protein subunits gradually increased with increasing urea concentrations, but the hydrodynamic radii and polydispersity indexes of the subunits in very alkaline solutions decreased. Both proteins were denatured by 6-8 M urea solutions through a two-step denaturation mechanism. However, some structural transitions were detected by changing the pH of solutions. Solubilities of glycinin and beta-conglycinin are significantly related to the concentration of urea in solution as well as the pH value.