Immobilization of dopamine transporter onto liposomes for capillary electrophoresis analysis

Model biomembrane which can mimic the biofunction of cell is being intensively craving for in the research field of proteomics, drugs and metabolism and so on. Liposomes have very similar structure with cell plasma membrane, which have been extensively used as model biomembrane to mimic processes occurring at cell membranes. But to the best of our knowledge, there have still been no reports yet involved in integrating plasma membrane proteins with mimic biomembrane acting as pseudo-stationary phase in capillary electrophoresis (CE) to concentrate on the biological activity of proteins. In this paper, we first attempted to immobilize dopamine transporter (DAT), which was extracted from the brains of the Wistar rats, into the liposomes to make the protein-liposome conjugate. The conjugate which may be regarded as the mimic cell was added into the running buffer as the pseudo-stationary phase in CE. The relationship between the concentration of proteins and the effective mobility of the analyte dopamine (DA) was investigated to elucidate the characteristics of the conjugate. Besides, nomifensine, which is the competitive inhibitor of DAT and has specific interaction with DAT contained in the conjugate, was added into the running buffer to study its influence on the binding between DAT and DA. Our results showed that the proteins containing DAT obtained from the brains of Wistar rats were indeed immobilized into the liposomes and were always keeping its biological activity during the process of CE.