Probing the binding of thioTEPA to human serum albumin using spectroscopic and molecular simulation approaches

Abstract

The present work is devoted to probing the molecular interaction of N,N′,N″-triethylenethiophosphoramide (thioTEPA) with human serum albumin (HSA) using UV-visible and fluorescence spectroscopies. Further, molecular dynamics and molecular docking simulations were used to investigate the binding site of thioTEPA. The outcomes of the spectroscopic observations and also the Stern−Volmer and van’t Hoff equations were employed to determine the binding thermodynamic parameters. It was found out that the interaction of thioTEPA with HSA is enthalpy driven through a quenching mechanism that is both static and dynamic at domain I of HSA. No significant changes in the local and overall secondary structure, polarity, and hydrophobicity of HSA were observed. The low values of binding free energies and binding constants are evidence for necessary high dosage of thioTEPA in chemotherapies. These results may be attributed to the spherical geometry and steric hindrance of the free vibrating aziridinyl groups of thioTEPA.