DETERGENT-ENABLED TRANSPORT OF PROTEINS AND NUCLEIC-ACIDS THROUGH HYDROPHOBIC SOLVENTS

It is demonstrated that proteins and nucleic acids can be transported through hydrophobic organic solvents (liquid membranes) via nonspecifi c complex formation with detergents, whereas no macromolecule transpor t is observed without the latter. A protein (or a nucleic acid) first interacts with an oppositely charged detergent due to hydrophobic ion pairing in the aqueous feed phase. The resultant hydrophobic complex r eadily partitions into an organic solvent and then into the aqueous re ceiver phase, where it dissociates. Experiments with (i) different det ergent/protein molar ratios, (ii) a range of unrelated organic solvent s as liquid membranes, and (iii) homologous detergents with hydrophobi c tails of varying lengths indicate that the protein flux through the membrane directly correlates with the partitioning of the protein-dete rgent complexes from the aqueous feed into the organic phase. Very lit tle protein transport was detected at detergent concentrations above t he critical micelle concentration, suggesting that individual detergen t molecules, rather than micelles, play the key role. The rate of the detergent-enabled protein transport is not a function of the protein m olecular weight, provided that enough detergent molecules bind to make the complex sufficiently hydrophobic; e.g., bovine serum albumin can be transported faster than insulin, which is less than 1/10th of its s ize.