PHASE-SEPARATION OF BIOMOLECULES IN POLYOXYETHYLENE GLYCOL NONIONIC DETERGENTS

The advantage of aqueous two-phase systems based on polyoxyethylene de tergents over other liquid-liquid two-phase systems lies in their capa city to fractionate membrane proteins simply by heating the solution o ver a biocompatible rang of temperatures (20 to 37 degrees C). This pe rmits the peripheral membrane proteins to be effectively separated fro m the integral membrane proteins, which remain in the detergent-rich p hase due to the interaction of their hydrophobic domains with detergen t micelles. Since the first reports of this special characteristic of polyoxyethylene glycol detergents in 1981, numerous reports have conso lidated this procedure as a fundamental technique in membrane biochemi stry and molecular biology. As examples of their use in these two fiel ds, this review summarizes the studies carried out on the topology, di versity, and anomalous behavior of transmembrane proteins on the distr ibution of grycosyl-phosphatidylinositol-anchored membrane proteins, a nd on a mechanism to describe the pH-induced translocation of viruses, bacterial endotoxins, and soluble cytoplasmic proteins related to mem brane fusion. In addition, the phase separation capacity of these poly oxyethylene glycol detergents has been used to develop quick fractiona tion methods with high recoveries, on both a micro- and macroscale, an d to speed up or increase the efficiency of bioanalytical assays.