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.