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Primary electron transfer kinetics in membrane-bound Rhodobacter sphaeroides reaction centers: a global and target analysis


, : Primary electron transfer kinetics in membrane-bound Rhodobacter sphaeroides reaction centers: a global and target analysis. Biochemistry 36(38): 11360-8

Absorbance difference kinetics were measured on quinone-reduced membrane-bound wild type Rhodobacter sphaeroides reaction centers in the wavelength region from 690 to 1060 nm using 800 nm excitation. Global analysis of the data revealed five lifetimes of 0.18, 1.9, 5.1, and 22 ps and a long-lived component for the processes that underlie the spectral evolution of the system. The 0.18 ps component was ascribed to energy transfer from the excited state of the accessory bacteriochlorophyll (B*) to the primary donor (P*). The 1.9 ps component was associated with a state involving a BChl anion absorbing in the 1020 nm region. This led to the conclusion that primary electron transfer is best described by a model in which the electron is passed from P* to the acceptor bacteriopheophytin (H-L) via the monomeric bacteriochlorophyll (B-L), with the formation of the radical pair state P+B-L-. An analysis assuming partial direct charge separation from B* (Van Brederode, M. E., Jones, M. R., and Van Grondelle, R. (1997) Chem. Phys. Lett. 268, 143-149) was also consistent with the data. Within the framework of a five component model, the 5.1 and 22 ps lifetimes were associated with charge separation and relaxation of the P+H-L- radical pair state respectively, providing a description which adequately accounted for the complex kinetics of decay of P*. Alternatively, by assuming that the 5.1 and 22 ps components originate from a single component with a multi-exponential decay, a simpler analysis with only four components could be employed, resulting in only a small increase (7%) in the weighted root mean square error of the fit. In both descriptions part of the decay of P* proceeds with a lifetime of about 2 ps. The relative merits of these alternative descriptions of the primary events in light-driven electron transfer are discussed. Similar measurements on YM210H mutant reaction centers revealed four lifetimes of 0.2, 3.1, and 12 ps and a long-lived component. The 3.1 and 12 ps lifetimes are ascribed to multi-exponential decay of the P* state. The differences with the WT data are discussed.

US$19.90

PMID: 9298955

DOI: 10.1021/bi9707943


Other references

Caplan, A.L., 1996: Communitarian bioethics: reasons for pessimism. Responsive Community 7(1): 93-95

Drevets, D.A.; Elliott, A.M., 1995: Fluorescence labeling of bacteria for studies of intracellular pathogenesis. Interactions between intracellular bacterial pathogens and their eukaryotic cellular hosts or targets are often studied with fluorescence-based techniques such as fluorescence microscopy and flow cytometry. We tested whether the intracellular bact...

Sibaja, R.A.; Schmidt, G.H., 1975: Release of oxytocin in the cow during milking. Jugular vein oxytocin concn. were determined at 15-s intervals on 10 Holstein-Friesian cows during milking. Oxytocin ranged from 0.5 mu U/ml plasma prior to udder washing to 652.7 mu U/ml plasma at 1 min after application of teatcups. Results indi...

Sani, R.K.; Peyton, B.M.; Smith, W.A.; Apel, W.A.; Petersen, J.N., 2002: Dissimilatory reduction of Cr , Fe , and U by Cellulomonas isolates. The reduction of Cr(VI), Fe(III), and U(VI) was studied using three recently isolated environmental Cellulomonas sp. (WS01, WS18, and ES5) and a known Cellulomonas strain (Cellulomonas flavigena ATCC 482) under anaerobic, non-growth conditions. In...

Van Sande, M.; Karcher, D.; Lowenthal, A., 1964: Electrophoretic characterization of spinal proteins. Protides Biol Fluids 12: 253-254

Martin Prevel, P., 1978: The role of mineral elements in plants. The principal roles of each of the major and minor elements are reviewed, and their normal concentrations and distribution within the plant are indicated.

Aronow, W.S.; Ahn, C.; Kronzon, I., 1995: Echocardiographic findings associated with atrial fibrillation in 1,699 patients aged greater than 60 years. American Journal of Cardiology 76(16): 1191-1192

Hedley I.G., 1971: The Weak Ferromagnetism of Goethite (alpha --FeOOH). Origin, chemical analysis, paleomagnetism.

Stiles, J.H.; Jones, R.H., 2001: Top-down control by the red imported fire ant (Solenopsis invicta). Top-down control by predaceous insects has rarely been demonstrated in terrestrial communities, but invasive species may be particularly suited to exert such control. The red imported fire ant, Solenopsis invicta, has strong interactions with spid...

Young, John, 1994: Is stroke better managed in the community?. British Medical Journal 309(6965): 1356-1357