Impact of Intrinsic Hydrophobicity of Bile Salts on the Inhibition of Temperature-Induced Aggregation of Bovine Serum Albumin.

Abstract

Bile salts are highly hydrophobic biosurfactants known for their unconventional structure and abnormal micellization properties, which aid in several biological processes. The intrinsic hydrophobicity of bile salts plays a pivotal role during the binding interactions of these molecules with other biomolecules. The inhibition effects of three bile salts, sodium taurocholate (NaTC), sodium cholate (NaC), and sodium deoxycholate (NaDC), on the temperature-induced aggregation of BSA are explored. The results acquired from the Thioflavin T (ThT) assay and circular dichroism (CD) experiments demonstrate that all three bile salts can inhibit the BSA aggregation. Additionally, NaDC can have a prominent aggregation inhibition propensity for BSA compared to the other two bile salts. The inhibitory action of three bile salts toward BSA aggregation followed a particular order, complementing their intrinsic hydrophobicity. Further, binding interactions of native BSA with bile salts are characterized by tryptophan fluorescence emission, fluorescence lifetime studies, site marker studies, isothermal titration calorimetry, and thermal melting experiments. The results of these studies substantiate that bile salts bind to the native protein through strong hydrophobic forces and provide significant stabilization to the native conformation of the protein, which subsequently impedes the protein from aggregating.