Effect of a Synthesized Amyl-Glycine1, 10-Phenanthroline Platinum Nitrate on Structure and Stability of Human Blood Carrier Protein, Albumin: Spectroscopic and Modeling Approaches

In the present study, biological evaluation of a new synthesized anti-cancer compound, amyl-glycine1, 10-phenanthroline Platinum nitrate (Pt(II) complex), was investigated at different temperatures by spectroscopic methods (far-UV circular dichroism (CD) and fluorescence) and modeling methods (docking and FRET). Human serum albumin (HSA), one of the vital proteins in drug delivery system in the body, was used as a target protein. The Pt(II) complex is able to quench the intrinsic fluorescence of HSA considerably. Binding and thermodynamic parameters of the interaction between the protein and the ligand were analyzed by fluorescence quenching method. The far-UV CD spectra revealed that the secondary structure of HSA did not show any noticeable change upon interaction with Pt(II) complex at both 25 and 37°C. The calculation of fluorescence resonance energy transfer (FRET) confirmed that quenching mechanism is static, and the observed distance between the donor and acceptor is 1.18 nm. Molecular docking results are in agreement with experimental data suggesting that there is one site on HSA at which Pt(II) complex binds spontaneously. Moreover, docking results together with FRET evaluation illustrated that Pt(II) complex is located near Trp214 at a distance of 1.96 nm. Our experimental and theoretical results indicated that the driving forces for Pt(II) complex interaction with HSA are hydrogen bonding and van der Waals interactions. The combination of molecular docking and spectroscopy methods suggested that use of this new Pt(II) complex as an anti-cancer agent, is an effective innovative approach in cancer chemotherapy providing a better understanding of effects of new designed drugs.