THERMODYNAMIC STUDIES ON THE INTERACTION BETWEEN DODECYL TRIMETHYL AMMONIUM BROMIDE AND HISTONE H A

The thermodynamic parameters of interaction between calf thymus histone H A and dodecyl trimethyl ammonium bromide (DTAB), a cationic surfactant, in aqueous solutions of pH 3.2, 6.4 and 10.0 were measured over a wide range of DTAB concentrations by equilibrium dialysis at 27°C and 37°C and are discussed. The data are used to determine the free energy from the Wyman binding potential theoretical model, and the enthalp y of interaction from the temperature dependence of the equilibrium constants using the van't Hoff relation. The data obtained for H A-DTAB are compared with the corresponding data for H A and sodium n-dodecyl sulphate (SDS) complexes. The difference between the cationic and anionic surfactants interaction in regard to histone H A is discussed