Characterization of the transmembrane serine receptor by capillary zone electrophoresis

Capillary zone electrophoresis (CZE) was applied to the characterization of the transmembrane serine receptor in biosynthetic samples. The serine rece ptor, otherwise known as Tsr (taxis to serine and repellents), is a 60,000 Dalton intrinsic membrane protein whose periplasmic domain (ligand binding domain) reversibly binds the amino acid serine. In general, the electrophor esis of intrinsic membrane proteins is difficult due to severe solubility p roblems and adsorption which occurs during the electrophoretic run. This is due to the tendency of these types of proteins to undergo aggregation, sel f-aggregation and precipitation in aqueous environments. The addition of pe rcentage levels of the surfactant, sodium dodecyl sulfate (SDS), to a tetra borate run buffer was shown to be effective both in enhancing the solubilit y of intact Tsr and in preventing the adsorption of intact Tsr to the fused -silica capillary wall during electrophoretic analysis. Critical separation parameters such as run buffer concentration, surfactant concentration and surfactant type were optimized to give the best separation profiles.