Reversed micelles are water-in-oil microemulsion droplets stabilized by surfactants in apolar solvents, and have been widely studied to extract proteins with liquid-liquid extraction process. Many enzymes have been successfully extracted by reversed micelles without too much bioactivity loss. This work describes the extraction and back-extraction, through the contact of equal volumes of phase, of an alkaline protease from the intestine crude extract of Nile tilapia (Oreochromis niloticus), the second most important fish in Brazilian aquaculture, using 50 mM AOT/isooctane reversed micelles. The time, speed and temperature of agitation for the extraction and back-extraction were studied. The best condition for the extraction was found to be with 10 min, 1,650 rpm and at 45°C. The back-extraction was obtained through of the contact of a new aqueous phase of 100 mM Tris HCl buffer containing 150 mM KCl, at pH 8.0. The best condition for the back-extraction was found to be with 10 min, 1,650 rpm and at 25°C. Under these conditions it was possible to obtain a purification factor of 6.3, suggesting that the liquid-liquid extraction process can be considered as an alternative to the classical precipitation method for the separation of biomolecules.

Supported by PIBIC/CNPq/UFPE.