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, DeltaS 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 Förster 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.