Optical, structural and thermodynamic properties of the interaction between tradimefon and serum albumin

The biological toxicity of a chloric pesticide, tradimefon to bovine serum albumin (BSA) were studied by fluorescence and absorption spectroscopy. The fluorescence quenching mechanism analysis indicates the quenching of BSA by TDF was caused by BSA–TDF complex formation and electrostatic interaction played major role in the reaction. The number of binding sites n and observed binding constant Kb was measured by fluorescence quenching method. The thermodynamic parameters ΔHθ, ΔGθ, ΔSθ at different temperatures were calculated, and the distance r between donor (BSA) and acceptor (TDF) was obtained according to Förster theory of non-radiation energy transfer. Three-dimensional fluorescence spectra, circular dichroism (CD) spectra and synchronous fluorescence spectra were used to investigate the structural change of BSA molecules with addition of TDF and the mechanism of binding reaction was analyzed at molecular level.