Promotion and Modulation of Amyloid Fibrillation of Bovine Beta-Lactoglobulin by Hydroxychalcones

Hydroxychalcones are naturally occurring compounds having biological relevance. This work demonstrates the synthesis of some chalcones having hydrophobic and polar groups and the investigation of their effect on the stability of a model protein beta-lactoglobulin (β-lg). An easy and simple method (Simon-Smith) was utilized to synthesize the four chalcone compounds. The binding of the chalcone molecules to the protein destabilized the protein structure and subsequently exposed the hydrophobic cores resulting in the aggregation of β-lg under thermal conditions. Using multiple spectroscopic methods (UV-Vis, fluorescence, FT-IR), imaging techniques like TEM, and theoretical tools were used to monitor the formation of protein aggregation and to understand the underlying mechanism. Exposures of hydrophobic amino acid residues in the aqueous medium by binding of the chalcones are responsible for protein aggregation through protein-protein interactions. It is sensitive to the polarity of the hydroxychalcones. In this process, polar group-containing hydroxychalcones are less effective, and unsubstituted hydroxychalcones are most efficient in promoting the amyloid fibrillation of β-lg.