Interfacial transport processes in the reversed micellar extraction of proteins

Interfacial mass transfer coefficients for the transfer of the proteins α-chymotrypsin and cytochrome c between a bulk aqueous and a reversed micellar phase were measured using a stirred diffusion cell. The strong dependence of interfacial forward transport kinetics on pH and salt concentration indicates the dominant role that charge interactions play in this system. This role is elucidated theoretically by determining the electrostatic interactions between a protein particle and the bulk interface, and the degree to which that interface will deform in response to these interactions. Back transfer rates were found to be three orders of magnitude slower than those for forward transfer. The dependence of these rates on aqueous pH suggests that coalescence of the protein-filled micelle with the bulk interface dominates the desolubilization kinetics.