Spectroscopic Studies on the Interaction of A dichlorido-bridged dinuclear copper(II) complex [Cu2Cl4(C17H20Cl2N2)2] of diamine with bovine serum albumin

The interaction of the complex [Cu₂Cl₄(C₁₇H₂₀Cl₂N₂)₂] with bovine serum albumin (BSA) has been investigated by fluorescence spectroscopy and UV-absorption under simulative physiological conditions. The experimental results indicated that the quenching mechanism of fluorescence of BSA by complex was a static quenching process. The binding constants (K_a) and the number of binding sites(n) were calculated ; The thermodynamic parameters, the enthalpy change (ΔH) and the entropy change (ΔS) were calculated to be -13.01kJ/mol, 13.35 kJ/mol respectively, which indicated that the interaction between complex and BSA was driven, mainly by electrostatic force. The negative sign for Gibbs free energy (AG = -89.98 kJ/mol) means that the interaction process is spontaneous. The binding distance between complex and BSA was calculated to be 3.79 nm on the basis of the Foster´s theory, which indicates the energy transfer from BSA to complex can occur. The synchronous fluorescence and UV-absorption of BSA showed that complex could change the conformation of BSA.