Membrane proteins are one of the most important target proteins with the various biological functions in drug discovery and elucidation of biological phenomena. Nonetheless, the data of structure and dynamics of membrane proteins are very limited, compared to that of water-soluble proteins, because of serious difficulties in handling of membrane proteins. Therefore the novel surfactants and phospholipids useful for membrane protein reconstitution have been desired for a long time. We have designed and synthesized a novel partially fluorinate phosphatidylcholine, 1,2-di(11,11, 12,12,13,13,14,14,14-nonafluorotetradecanoyl)-sn-glycero-3-phosphatidylcholine (diF4H10-PC), an analog of a common phosphatidylcholine DMPC, which is applicable to biophysical studies of membrane proteins.
The partial fluorination of DMPC led to very interesting membrane physical properties: significant decrease in the gel-to-liquid crystalline phase transition temperature to ～5 oC and increase in polarity in the hydrophilic/hydrophobic interface region.1 2 Furthermore we succeeded in reconstituting a photoreceptor membrane protein, bacteriorhodopsin (bR), into diF4H10-PC liposome. The reconstituted bR retained the trimeric structure even after the chain melting phase transition of lipid bilayers at least up 40 oC and showed a photocycle similar to native purple membrane, which is in stark contrast with the previous studies on bR reconstituted in DMPC.3 These experimental results suggest that the novel partially fluorinated phosphatidylcholine, diF4H10-PC, is very useful for membrane protein research.