Inhibition of glycinin thermal aggregation by an artificial chaperone sodium dodecyl sulphate

Summary Poor solubility caused by thermal aggregation usually limits the utilisation of soy proteins in food industry. In this study, the anionic surfactant, sodium dodecyl sulphate (SDS), was found to be effective in suppressing thermal aggregation of glycinin which was the main composition of the insoluble aggregates of soy proteins. Turbidity, dynamic light scattering, surface tension, circular dichroism and fluorescence spectra analysis were used to reveal the mechanism for the inhibitory of thermal aggregation by SDS. Bound to SDS, the exposed hydrophobic groups on the protein molecules were covered by the ionic head groups of SDS. The approaching of the particles was unavailable in the presence of the strong electrostatic repulsive force. Therefore, the particles remained stable and disperse. Thermal aggregation was not effectively suppressed until the binding sites which interacted with SDS on the glycinin molecules were saturated. The strategy for improving the solubility of food protein was also discussed.