In Vitro Binding of Furadan to Bovine Serum Albumin

Under physiological conditions, the interaction between furadan (FRD) and bovine serum albumin (BSA) was investigated by spectroscopy including fluorescence emission, UV-visible absorption, scattering, circular dichroism (CD) spectra, synchronous and three-dimensional fluorescence spectra. The observed binding constant K _b and the number of binding sites n were determined by the fluorescence quenching method. The distance r between donor (BSA) and acceptor (FRD) was obtained according to the Förster theory of non-radiation energy transfer. The enthalpy change (ΔH ^θ ), Gibbs energy change (ΔG ^θ ) and entropy change (ΔS ^θ ) at four different temperatures were calculated. The process of binding was proposed to be a spontaneous process since the ΔG ^θ values were negative. The positive ΔS ^θ and ΔH ^θ values indicated that the interaction of FRD and BSA was driven mainly by hydrophobic interactions. The addition of FRD to BSA solutions leads to enhancement in scattering intensity, exhibiting the formation of an aggregate in solution. CD spectra, synchronous and three-dimensional fluorescence spectra were used to measure the structural change of BSA molecules with FRD present.