Abstract The interactions of fluoride with bovine serum albumin(BSA), bovine hemoglobin (BHb) and ovalbumin (OVA) were studied in acetate buffer (pH = 5.68), at 288K, 298K and 308K, using a fluoride ion-selective electrode. The data for the fluoride-protein systems were treated according to the Klotz equation, and the number of binding sites and the binding constants were found. It was shown that the number of fluoride-binding sites(n) in BSA and BHb increases with increasing temperature, while for OVA, the value of n decreases under the same condition. At the same time, our studies indicate that the binding constants of BSA and BHb systems first decrease and then increase with increasing temperature. While for OVA, the results are reverse. These were reasonably interpreted with the structural and thermodynamic factors. The thermodynamic function changes of the binding process （△G, △H, △S）at different temperatures were calculated with thermodynamic equations, which show that the binding power between F– and proteins is mainly electrostatic interaction.

Key words: ion-selective electrode, fluoride, bovine serum albumin, bovine hemoglobin, ovalbumin, binding