Binding of Halide Ions to Bovine Serum Albumin and Hemoglobin: Studied with Ion-Selective Electrodes

摘要

The interactions of F–, Br– and I– with bovine serum albumin (BSA) and with hemoglobin (Hb) werestudied in acetate buffers of pH 5.68, at different temperatures, by using ion-selective electrodes. Thedata for the anion-protein systems were treated according to Klotz equation, and the number of bindingsites and the binding constants were determined. It is shown that the binding sites of F– on BSA and onHb molecules are more than those of Br– and I–, and that the number of the binding sites for F–, Br– andI– on BSA and on Hb molecules increases with increasing temperature. This study also indicates thatthe binding constants for the interactions of F–, Br– and I– with BSA and with Hb gradually decrease asthe size of halide ions increases. In addition, as temperature increases, the binding constants graduallydecrease. These were reasonably interpreted with the structural and thermodynamic viewpoints. Thethermodynamic studies indicate that the interactions of halide ions with proteins are mainlyelectrostatic interaction.