Elucidating the binding mechanism of a cholesterol absorption inhibitor with a serum albumin: spectroscopic, zeta potential, voltammetric and computational studies

Biomolecular binding of a potential drug, ezetimibe (EZT) with bovine serum albumin (BSA) was investigated by spectroscopic and electrochemical methods besides molecular modeling studies. Fluorescence measurements showed that the fluorescence intensity of BSA was quenched by EZT with a slight blue shift in the emission wavelength (from 346 to 340 nm). The values of binding constant, number of binding molecules and Stern–Volmer quenching constant of EZT-BSA  system was calculated at different temperatures. The values of Stern–Volmer quenching constant increased with temperature indicating the presence of dynamic quenching mechanism. The probable location of  EZT within the protein cavity (subdomain IIIA) was explored by docking studies and displacement experiments. Based on the values of free energy change, enthalpy change and entropy change, hydrophobic interaction was proposed to be the main factor that stabilized the  EZT-BSA interaction. Studies on zeta potential of BSA unraveled the role of electrostatic interaction between EZT and BSA. In addition, synchronous fluorescence and circular dichroism spectral studies revealed the conformational changes occurred in BSA upon binding of EZT.