Liquid-liquid phase separation of a surfactant-solubilized membrane protein.
Solubilization of membrane proteins requires surfactants, whose structural properties play a crucial role in determining the protein phase behavior. We show that ionization of a pH-sensitive surfactant, lauryldymethylamino-N-oxide, bound to the bacterial photosynthetic Reaction Center, induces protein phase segregation in micrometric "droplets." Liquid-liquid phase separation takes place in a narrow pH range, is promoted by increasing temperature, and vanishes by adding salt. After a fast initial droplet growth, the nearly arrested kinetics at a later stage leaves the system in a finely divided, long-lasting emulsified state.
Piazza
Roberto
R
INFM-Politecnico di Milano, Dipartimento di Ingegneria Nucleare, via Ponzio 34/3, I-20133 Milano, Italy. roberto.piazza@polimi.it
Pierno
Matteo
M
Vignati
Emanuele
E
Venturoli
Giovanni
G
Francia
Francesco
F
Mallardi
Antonia
A
Palazzo
Gerardo
G
D004123:Dimethylamines / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008027:Light; D008565:Membrane Proteins / Q000737:chemistry*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D012242:Rhodobacter sphaeroides / Q000737:chemistry; D012542:Scattering, Radiation; D012995:Solubility; D013501:Surface-Active Agents / Q000737:chemistry*
D004123:Dimethylamines; D008565:Membrane Proteins; D045322:Photosynthetic Reaction Center Complex Proteins; D013501:Surface-Active Agents; C014518:dodecyldimethylamine oxide