Influence of the oxidation state of the metal center on the interaction of ruthenium complex with HSA

摘要

The binding of [Ru(H2O)(2)(bpydip)](2+/3+) (bpydip = N,N'-bis[1-(2-pyridinyl)ethylidene]-1,3-propanediamine) to human serum albumin was investigated by spectroscopic techniques. The hydrophobic interaction between ruthenium(II) complex and HSA was spontaneous with the binding constants calculated to be 1.27 x 10(3) dm(3) mol(-1) (298 K), 7.74 x 10(3) dm(3) mol(-1) (303 K), and 9.46 x 10(3) dm(3) mol(-1) (308 K). The binding of ruthenium(III) complex to HSA induced the hybrid quenching mechanism with the binding constants estimated to be 1.25 x 10(9) dm(3) mol(-1) (298 K), 1.31 x 10(9) dm(3) mol(-1) (303 K), and 3.57 x 10(9) dm(3) mol(-1) (308 K). Thermodynamic parameters (Delta H = 76 kJ mol(-1); Delta S = 515 J mol(-1) K-1) indicated that hydrophobic forces played a major role in the binding of ruthenium(III) complex to HSA. In addition, the number of binding sites (n) for ruthenium(II) complex was approximately 1, whereas ruthenium(III) complex recorded 2. CD data indicated that the secondary structure of HSA is not changed in the presence of complexes.