Dynamic and Thermodynamic Investigation on the Interaction of Bovine Serum Albumin with an Anticancer Pt Complex Containing Dithiocarbamate Using Molecular Docking and Spectroscopic Methods

Cisplatin is used for human cancers treatment, such as bladder and ovarian, endometrial and cervical, head and neck, and testicular cancer, but its clinical use has been limited by some serious side effects. Therefore S,S donor ligands such as dithiocarbamates can be used to prepare anticancer Pt-drugs and reduce some side effects. The purpose of this study is the interaction ability of designed Pt complex, [Pt(bpy)(tertamyl.dtc)]NO3, where bpy is bipyridine and tertamyl-dtc is (2-methyl butan-dithiocarbamate), with bovine serum albumin (BSA) using fluorescence emission titration, UV-Vis spectroscopy, and molecular docking methods. The obtained negative values of enthalpy, Delta H-b(0), and entropy, Delta S-b(0), showed that a major binding mode between Pt complex and BSA is the van der Waals and hydrogen bond. The negative value of Gibbs free energy achieved via the UV-Vis technique also exhibited a spontaneous interaction. In addition, the results related to emission titration displayed that the fluorescence quenching of protein by Pt complex is a static quenching mechanism. Moreover, the binding parameters, including apparent biomolecular quenching constant (k(q)), the number of binding sites (n), and binding constant (K-b) were obtained by the Stern-Volmer equation. These values of K-b, k(q), and n were also obtained as 3 x 10(8) M-1, 3 x 10(14) M-1 S-1, and 1.4, respectively. By the use of spectroscopic kinetics model, this interaction was studied and the result showed a second-order type. Finally, the binding of Pt complexes to BSA was verified by the molecular docking method. The binding free energy and K-i for the Pt compounds were obtained as -6.6 kcal mol(-1) and 14.48, respectively. The results of molecular docking demonstrate the position of binding of Pt complex on BSA is the site I in the subdomain IIA.