Primary charge separation in mutant reaction centers of Rhodobacter capsulatus
Abstract
Excited-state decays of the special pair of Rhodobacter capsulatus and 10 mutants as a function of temperature are presented. The mutations are at the symmetry-related sites L181 and M208. All the decays are nonexponential, although the degree of nonexponentially depends strongly on the mutant and the temperature. We correlated the changes in decay time with mutation-induced changes in the redox potential of the ground state of the special pair. The qualitative form of the decays led us to explore a model based on a small Gaussian distribution of free energy gaps for the electron-transfer process. The model is used to estimate the reorganization energy arising from low-frequency protein and intramolecular modes coupled to the electron transfer. Our fitting procedure gives values of 1250 and 500 cm^(-1) at 292 and 22 K, respectively. A consideration of possible errors leads us to conclude that the room temperature value could be no larger than twice the fitted value (i.e., ≤ 500 cm^(-1)). The implications of our results for the mechanism of primary charge separation are discussed.
Additional Information
© 1993 American Chemical Society. Received: July 15, 1993; In Final Form: October 15, 1993. We dedicate this paper to the memory of Gerhard Closs. His penetrating intellect and vast knowledge would have certainly improved our paper had we been able to discuss it with him. We especially thank Prof. G. Small for providing us with unpublished work and stimulating discussions. We also thank Prof. J. Jortner and Prof. S. Mukamel for their important suggestions and discussions. We appreciate preprints and discussions provided by Profs. D. Chandler and R. Friesner and the conversation related to electron-transfer mechanisms. This work was supported by a grant from the National Science Foundation (G.R.F.), the Department of Energy, Office of Basic Energy Sciences (J.R.N.), and Office of Health and Environmental Research (D.K.H. and M.S.) under Contract W-31-109-Eng-38. M.S. is also supported by US. Public Health Service Grant GM36598. This work is a publication of the Center for Photochemistry and Photobiology at the University of Chicago.Additional details
- Eprint ID
- 86752
- Resolver ID
- CaltechAUTHORS:20180601-142455566
- NSF
- W-31-109-Eng-38
- Department of Energy (DOE)
- GM36598
- NIH
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2018-06-01Created from EPrint's datestamp field
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2021-11-15Created from EPrint's last_modified field