Study on interaction of α-amylase from Bacillus subtilis with cetyl trimethylammonium bromide

The interaction of cetyl trimethylammonium bromide (CTAB) with α-amylase from Bacillus subtilis was investigated at 25 °C and various experimental conditions, such as pH, ionic strength and urea concentration. The binding data were measured using CTAB-membrane selective electrodes as a simple, fast, cheap and accurate method. The obtained binding isotherms were analyzed using Wyman binding potential concept. The results represent the highest binding affinity at 10−3 M of NaBr respect to other salt concentrations. The less binding affinity at pH 9.7 with respect to pH 6.5 is related to increasing of protein self aggregation with pH. The binding data analysis at various urea concentrations also shows that the predominate unfolding of α-amylase occurred in the urea concentration range of 3-5 M.