Charge displacements in interfacial layers containing reaction centers.
Reaction centers from the photosynthetic bacterium Rhodobacter sphaeroides were oriented in phospholipid interfacial layers adsorbed to a Teflon film separating two electrolyte-filled compartments of a Teflon cell. Light-induced voltage changes were measured as a function of time across electrodes immersed in the cell compartments. The experimental system is characterized both experimentally and theoretically to relate the measured signals to the light-induced displacement currents in the reaction centers. Mathematical relations between the measured signals and the distances and geometries of the charge-transfer reactions are derived. At pH 8.0 the reaction centers were found to be oriented with approximately 60% of the population oriented with the donor facing the aqueous phase. The density of the reaction centers in the layer was approximately 10(11) cm-2, which is close to that found in the native system. Reconstitution of the secondary quinone, QB, in 90% of the RCs was achieved with an approximately 100-fold excess of ubiquinone in the vesicle preparation.
Department of Biochemistry and Biophysics, Göteborg University and Chalmers University of Technology (Medicinaregatan 9C), P.O. Box 462, SE-405 30 Göteborg, Sweden.
P
P
Brzezinski
A
A
Messinger
Y
Y
Blatt
A
A
Gopher
D
D
Kleinfeld
D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods; D004579:Electron Transport; D007202:Indicators and Reagents; D008027:Light; D008051:Lipid Bilayers; D008962:Models, Theoretical; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry* / Q000528:radiation effects; D012242:Rhodobacter sphaeroides
D007202:Indicators and Reagents; D008051:Lipid Bilayers; D045322:Photosynthetic Reaction Center Complex Proteins