Interactions of a Ruthenium-Ketoprofen Compound with Human Serum Albumin and DNA: Insights from Spectrophotometric Titrations and Molecular Docking Calculations

The compound [Ru2O(keto)(2)(py)(6)](PF6)(2), keto=ketoprofen and py=pyridine, interacts with calf thymus-DNA with K-b=1.08x10(4) M-1. It efficiently quenches HSA fluorescence in different temperatures, with Ksv values in the 10(4)-10(5) M-1 range, both by dynamic and static mechanisms. The data provided by the double logarithmic and van't Hoff approximations indicated a moderate (K-b approximate to 10(4) M-1) and spontaneous (Delta G<0) interaction, being enthalpically driven (Delta H=-27.1 kJ mol(-1) and Delta S=-5.3 J mol(-1) K-1). Molecular docking calculations confirmed that the binuclear compound interacts with HSA more strongly than with DNA. The occurrence of a high contribution from electrostatic forces was observed, fully consistent with the bicationic nature of [Ru2O(keto)(2)(py)(6)](PF6)(2). The molecular docking results also revealed that the interaction occurs in an external subdomain, explaining the lack of significant conformational changes in the protein, as probed by circular dichroism spectra.