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

Abstract

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 (Ka) 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.