IMPROVING PROTEIN EXTRACTION YIELD IN REVERSED MICELLAR SYSTEMS THROUGH SURFACE-CHARGE ENGINEERING

The mechanism of extraction of rat cytochrome b(5) from water into a s odium dioctylsulfosuccinate (AOT) micellar organic phase was studied u sing protein engineering of surface charged residues. The extraction b ehavior of native cytochrome b(5) and modified proteins with substitut ions of the type glutamic acid --> lysine at positions 44 (E44K), 56 ( E56K), and 92 (E92K), was studied as a function of pH. The results ind icate that an important mechanism of extraction is an electrostatic in teraction of this protein with the negatively charged surfactant. We d emonstrate that it is possible to improve extraction by engineering th e protein surface charge, increasing the driving force responsible for the protein transfer to the micellar phase. (C) 1994 John Wiley and S ons, Inc.