Unravelling the binding mechanism of benproperine with human serum albumin: A docking, fluorometric, and thermodynamic approach.

The interaction between benproperine (BEN) and human serum albumin (HSA) has been simulatively and experimentally investigated based on docking, fluorometric, thermodynamic, and spectroscopic approach. The blind Autodock docking study first recognized the hydrophobic cavity of HSA at Domain IB as the probable binding site for BEN. BEN bound to HSA via a static quenching mechanism, resulting in the formation of BEN-HSA complex confirmed by fluorescence quenching and time-resolved fluorescence. Fluorescence titration and isothermal titration calorimetry (ITC) revealed that the binding mode between BEN and HSA owning moderate affinity (binding constant at 104 magnitude) was mainly driven by electrostatic attraction and hydrophobic interaction. Circular dichroism (CD) spectra suggested upon Addition of BEN induced the conformational changes on HSA with α-helix decreasing. Due to the conformational rearrangements, BEN-HSA complex was stabilized by several non-covalent bonds. This work first clarified the progress in binding mechanism of benproperine with human serum albumin and then provided fresh insights into this drug transportation and metabolism.