Characterization of the interaction between a platinum(II) complex and human serum albumin: spectroscopic analysis and molecular docking

In this study, the interaction between (2,2'-bipyridine)(pyrrolidinedithiocarbamato) platinum(II) nitrate, [Pt(bpy)(pyr-dtc] NO3, and human serum albumin (HSA) was investigated by various spectroscopic methods (UV-vis, fluorescence, CD and FT-IR) and molecular docking technique at three temperatures. UV-vis absorption spectroscopy showed that Pt(II) complex can denature the protein at moderate concentrations. The results of emission quenching at two temperatures has revealed that the quenching mechanism of Pt(II) complex with HSA was static quenching mechanism. Binding constants (K), binding site number (n) and corresponding thermodynamic parameters Delta G degrees, Delta H degrees and Delta S degrees were calculated and revealed that hydrophobic forces played a major role when Pt(II) complex interacted with HSA. The binding distance (r) between above complex and HSA based on Forster's theory of non-radiation energy transfer was calculated as 3.22 nm. Alterations of HSA secondary structure induced by complex were confirmed by FT-IR and CD measurements. Also, a molecular docking study was performed for identification of key structural features of binding of the Pt complex into the receptor and predicting bioactive conformers. Our results may provide valuable information to understand the mechanistic pathway of drug delivery and to pharmacological behavior of drug.