One-step separation of lysozyme by reverse micelles formed by the cationic surfactant, cetyldimethylammonium bromide

Lysozyme was selectively extracted from reconstituted freeze-dried egg-white, using reverse micelles formed by the cationic surfactant, cetyldimethylammonium bromide (CDAB). The major egg-white proteins, including ovalbumin and ovotansferrin, were solubilized into the organic phase while lysozyme was recovered in the aqueous phase. The solubilization behaviours of proteins were manipulated by processing parameters, including pH and salt concentration in the aqueous phase and concentration of surfactant in the organic phase. The optimum extraction was achieved with sodium borate buffer (50 mM, pH 9, no added KCl) and organic phase containing 50 mM CDAB. After the forward extraction, 96% of total lysozyme activity was recovered. Lysozyme was efficiently purified, more than 30-fold with only a single forward extraction. The suggested extraction procedure has advantages in terms of time and cost compared to traditional reverse micellar extraction which requires both forward and backward extraction steps.