Hemifluorinated surfactants: a non-dissociating environment for handling membrane proteins in aqueous solutions?
The instability of membrane proteins in detergent solution can generally be traced to the dissociating character of detergents and often correlates with delipidation. We examine here the possibility of substituting detergents, after membrane proteins have been solubilized, with non-detergent surfactants whose hydrophobic moiety contains a perfluorinated region that makes it lipophobic. In order to improve its affinity for the protein surface, the fluorinated chain is terminated by an ethyl group. Test proteins included bacteriorhodopsin, the cytochrome b(6)f complex, and the transmembrane region of the bacterial outer membrane protein OmpA. All three proteins were purified using classical detergents and transferred into solutions of C(2)H(5)C(6)F(12)C(2)H(4)-S-poly-Tris-(hydroxymethyl)aminomethane (HF-TAC). Transfer to HF-TAC maintained the native state of the proteins and prevented their precipitation. Provided the concentration of HF-TAC was high enough, HF-TAC/membrane protein complexes ran as single bands upon centrifugation in sucrose gradients. Bacteriorhodopsin and the cytochrome b(6)f complex, both of which are detergent-sensitive, exhibited increased biochemical stability upon extended storage in the presence of a high concentration of HF-TAC as compared to detergent micelles. The stabilization of cytochrome b(6)f is at least partly due to a better retention of protein-bound lipids.
Breyton
Cécile
C
Laboratoire de Physicochimie Moléculaire des Membranes Biologiques, UMR 7099, CNRS and Université Paris-7, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, F-75005 Paris, France.
Chabaud
Elodie
E
Chaudier
Yann
Y
Pucci
Bernard
B
Popot
Jean-Luc
JL
D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry; D001436:Bacteriorhodopsins / Q000737:chemistry; D002021:Buffers; D045346:Cytochrome b6f Complex / Q000737:chemistry; D003902:Detergents / Q000737:chemistry; D004983:Ethanolamines / Q000737:chemistry*; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry*; D008823:Micelles; D015394:Molecular Structure; D012996:Solutions; D013501:Surface-Active Agents / Q000737:chemistry*; D014325:Tromethamine / Q000737:chemistry*; D014867:Water
D001425:Bacterial Outer Membrane Proteins; D002021:Buffers; D003902:Detergents; D004983:Ethanolamines; C486370:HF-TAC; D006845:Hydrocarbons, Fluorinated; D008565:Membrane Proteins; D008823:Micelles; D012996:Solutions; D013501:Surface-Active Agents; D014325:Tromethamine; D014867:Water; C078167:OMPA outer membrane proteins; D001436:Bacteriorhodopsins; D045346:Cytochrome b6f Complex