Temperature Effects on the Ground State Absorption Spectra and Electron Transfer Kinetics of Bacterial Reaction Centers
It has been a general finding that the rates of many of the electron transfer processes in bacterial reaction centers are rather insensitive to temperature.1,2 In fact, often the rates actually increase slightly as the temperature is reduced. This is observed, for example, in Rb. sphaeroides reaction centers for electron transfer from P* to I (BPhL),3 from I− (BPhL −) to the primary quinone QA,4 and for the charge recombination reaction P+QA − → PQA.5–7 (P is the dimer of BChl molecules.) These findings have been taken to suggest that these reactions are activationless, or nearly so.
KeywordsElectron Transfer Reaction Center Electron Transfer Reaction Charge Recombination Electron Transfer Kinetic
Unable to display preview. Download preview PDF.
- 4.C. Kirmaier, D. Holten and W. W. Parson, Temperature and detection-wavelength dependence of the picosecond electron transfer kinetics measured in Rhodopseudomonas sphaeroides reaction centers. Resolution of new spectral and kinetic components in the primary charge separation process, Biochim. Biophvs. Acta 810: 33 (1985).CrossRefGoogle Scholar
- 6.M. R. Gunner, D. E. Robertson and P. L. Dutton, Kinetic studies on the reaction center protein from Rhodopseudomonas sphaeroides: The temperature and free energy dependence of electron transfer between various quinones in the QA site and the oxidized bacteriochlorophyll dimer, J. Phvs. Chem. 90: 3783 (1986).CrossRefGoogle Scholar
- 7.G. Feher, M. Okamura and D. Kleinfeld, Electron transfer reactions in bacterial photosynthesis: Charge recombination kinetics as a structure probe, in: “Protein Structure: Molecular and Electronic Reactivity”, R. Austin, E. Buhks, B. Chance, D. DeVault, P. L. Dutton, H. Frauenfelder and V. I. Gol’danskii, eds., Springer-Verlag, New York (1987).Google Scholar
- 9.C. Kirmaier, D. Holten and W. W. Parson, Picosecond study of the P+I−Q → P+IQ− electron transfer reaction in Rps. viridis reaction centers, Biophys. J. 49:586a (1986).Google Scholar
- 10.J. M. Hayes, J. K. Gillie, D. Tang and G. J. Small, Theory for spectral hole burning of the primary electron donor state of photosynthetic reaction centers, Biochim. Biophys. Acta (in press).Google Scholar
- 24.P. O. J. Scherer, S. F. Fischer, J. K. Horber and M. E. Michel-Beyerle, On the temperature-dependence of the long-wavelength fluorescence and absorption of Rhodopseudomonas viridis reaction centers, in: Antennas and Reaction Centers of Photosynthetic Bacteria,” M. E. Michel-Beyerle, ed., Springer-Verlag, Berlin (1985).Google Scholar