Liquid‐Liquid Extraction of a Recombinant Protein with a Reverse Micelle Phase

Recombinant cytochrome bs was extracted to a reversed micelle phase of a cationic surfactant (hexadecyltrimethylammonium bromide, CTAB) in cyclohexane/decanol and back‐extracted to a fresh aqueous phase. Depending on the experimental conditions, i.e., temperature, pH, and ionic strength, the extraction is controlled by either hydrophobic (pH close to the p I and high ionic strength) or electrostatic (pH far from the p I and low ionic strength) interactions. The protein interacts strongly with the surfactant aggregate once it is extracted to the organic phase, and it is very difficult to back‐extract it to a new aqueous phase.