Picosecond to nanosecond fluorescence kinetics as a function of emission wavelength is reported for isolated reaction centers of the purple bacterium R6. sphaeroides. New kinetic components of 12 ps and about 100 ps lifetime have been found in the fluorescence decay kinetics of the primary donor P\*
Electric field modulation of the fluorescence from Rhodobacter sphaeroides reaction centers
β Scribed by David J. Lockhart; Steven G. Boxer
- Publisher
- Elsevier Science
- Year
- 1988
- Tongue
- English
- Weight
- 752 KB
- Volume
- 144
- Category
- Article
- ISSN
- 0009-2614
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β¦ Synopsis
The fluorescence intensity from randomly oriented Rhodobacter (Rb.) sphaeroides photosynthetic reaction centers at 77 K increases in an applied electric field. This is ascribed to a net reduction in the rate of the initial electron transfer reaction which competes with fluorescence due to the effect of the field on the free energy of charge separation. Quantitative analysis of the fluorescence change in an electric field indicates that the difference in permanent dipole moment between the ground and initially formed excited state is greater than between the ground and emitting state.
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The excitation energy transfer between light-harvesting complex I (LH-I) and the photosynthetic reaction center (RC) of the purple bacterium Rhodobacter (Rb.) sphaeroides is investigated on the basis of the atomic level structures of the two proteins, assuming a ring-shaped model for LH-I. Rates of
Absorption-detected ODMR of reaction centers from different strains of Rhodobacter sphaeroides in the temperature range from 4.2 to 75 K are reported. The D and E parameters are independent of temperature. There is no indication of a temperaturedependent charge transfer admixture. Absorption ODMR in
External electric field modulation of charge separation 2nd recombinatton processes has been achieved in native photosynthetic reaction centers. Langmuir-Blodgett monolayer films of reaction centers isolated from the photosynthetic bacterium Rhodopseudomonas sphaero~des, have been incorporated into
**The cover picture shows** a model of the complex between the herbicide acifluorfen (yellow) and the bacterial reaction center of __Rhodobacter sphaeroides__ as derived from paramagnetic NMR constraints. The paramagnetic iron is shown in silver surrounded by the histidine ligands (magenta). For mor