Binding data analysis of the interaction of bovine hemoglobin with dodecyltrimethylammonium bromide

The interaction of dodecyltrimethylammonium bromide, as a cationic surfactant, with bovine hemoglobin, as a biopolymer, has been investigated at different temperatures by an equilibrium dialysis technique. The obtained binding isotherms have been analyzed and interpreted by the Wyman binding potential model and other thermodynamic parameters which have been extracted on the basis of this model. A new method of analysis for evaluating the binding isotherms and estimating the free energy change, Delta G(t), per mole of ligand has been proposed. The unusual behavior of the Scatchard plot at 300 K was analyzed in terms of two sets of binding sites. The first set of binding sites was considered as electrostatic and the second as hydrophobic. The free energy of interaction (<Delta G((v))over bar>) from the Wyman model was also resolved according to electrostatic and hydrophobic binding free energies.