Biopolymer–Surfactant Interaction 2: Kinetics of Binding of Cetyltrimethylammonium Bromide with Bovine Serum Albumin

Abstract

Abstract The results of the kinetics of binding of the surfactant cetyltrimethylammonium bromide (CTAB) with bovine serum albumin (BSA) under varied conditions of CTAB concentration, pH, ionic strength and temperature are presented. The kinetic process has been found to be comprised of either two or three stages; the rate constants of the first, second, and third stages follow the general order of k1 >> k2 > k3. The three-stage kinetic process has been observed at higher CTAB concentrations, higher temperature and in presence of the protein denaturant urea. The activation parameters for this three-stage kinetic process have been determined. Most entropies of activation have been found to be negative (a very few are positive) whereas the activation enthalpies and energies are both positive and negative. The enthalpy and entropy for all the kinetic stages in different environmental conditions have been found to compensate each other, whereas the free energy of activation has remained unaffected. A model for the three-stage kinetic process has been proposed.