Spectroscopic and docking molecular study of new anticancer Pt complex binding with human serum albumin

After synthesizing and identifying the nature of the new complex based on platinum metal, [Pt(NH₃)₂(butylgly)]NO₃, the interaction of this complex with human serum albumin (HSA) was performed by spectroscopy and molecular docking methods at two temperatures of 27 and 37 °C and under physiological conditions of the body. The toxicity test of this complex was performed on the MCF-7 cell line (IC₅₀ = 300 µM). Enthalpy, entropy, Gibbs free energy, binding constant, number of complex binding sites on the HSA, Scatchard diagrams, Hill coefficient, and Hill constant were calculated and then plotted via UV/Vis. According to the Gibbs free energy obtained at two temperatures of 27 and 37 °C (-20.6, -21.2 kJ mol^-1), the interaction was done spontaneously. Moreover, the melting temperature of human serum albumin with this complex; and the kinetics of this interaction (the second-order) were calculated. Using fluorescence at three temperatures of 25, 27, and 37 °C, the binding constant (2.9 × 10⁴, 1.0 × 10⁴, and 5.7 × 10³ M^-1), the quenching constant, average aggregation number of HSA, and the number of binding sites of the complex on the protein were obtained. As well, the static quenching mechanism was also observed. Molecular docking results showed that the site of binding of this complex to the HSA, is the site II subdomain IIIA, and the hydrogen and hydrophobic bonds are superior.