Biophysical and Molecular Docking Studies of Human Serum Albumin Interactions with a Potential Anticancer Pt(II) Complex

The interaction between [Pt(phen)(pyrr-dtc)]NO3 (where phen = 1,10-phenanthroline and pyrr-dtc = pyrrolidinedithiocarbamat) with human serum albumin (HSA) was studied by fluorescence, UV-Vis absorption, circular dichroism (CD) spectroscopy and molecular docking technique under like physiological condition in Tris-HCl buffer solution at pH 7.4. UV-Vis absorption spectroscopy indicates that the protein chain was unfolded upon the addition of Pt(II) complex. Experimental results imply that the Pt(II) complex has a strong ability to quench the intrinsic fluorescence of HSA through a static quenching process. Binding constants (Kb = 2.8, 2.6 and 2.5 × 105 M-1) and the number of binding sites (n ~ 1) were calculated. According to van't Hoff equation, the thermodynamic parameters revealed that hydrophobic forces played a major role when Pt(II) complex interacted with HSA. From the qualitative analysis data of CD spectra, the binding of Pt(II) complex to HSA induced conformational changes in this protein. Finally, a molecular docking was employed for identification of the active site residues and critical interactions involved.