Study of interaction between Aspergillus niger cellulase (ANC) and Cetyltrimethylammonium Bromide (CTAB) using surfactant membrane selective electrode

Abstract

The interaction of cetyltrimethylammonium bromide, CTAB, to Aspergillus niger cellulase, ANC, has been studied using potentiometric technique. Binding isotherms were obtained from the potentiometric technique and using the Wyman binding potential model, apparent binding constants were calculated. The obtained binding isotherms have been analysed and interpreted using the Wyman binding potential. The Gibbs free energy change calculated on the basis of the Wyman binding potential concept decreases with increasing amount of binding. The affinity of binding increased with increasing temperature, indicating an endothermic and essentially entropy driven process. On the other hand, studying of binding processes at various pH indicates that ANC has a more enthalpic stability and probably has a more packed structure at pH = 5 than that at pH = 7.5 and 10. Data analysis based on the Scatchard equation at various pH and temperatures shows a linear behavior with positive slope, indicating one set of binding sites.