Photochemical studies on the binding of an organic fluoride to bovine serum albumin

The interaction of fipronil (FPN), a pesticide containing fluorine, to bovine serum albumin (BSA) was studied by spectroscopy including fluorescence spectra, UV-Visible absorption, scattering spectra, circular dichroism (CD) spectra, synchronous and three-dimensional fluorescence spectra. The number of binding sites n and observed binding constant Kb was measured by fluorescence quenching method. The thermodynamic parameters Delta H, Delta G, Delta S at different temperatures were calculated and the results indicate that hydrophobic forces played major role in the reaction. The distance r between donor (BSA) and acceptor (FPN) was obtained according to the Forster theory of non-radiation energy transfer. The structural change of BSA molecules with addition of FPN was analyzed and the results may be helpful to biologists, chemists and therapeutists.