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Science 18 August 1995:
Vol. 269. no. 5226, pp. 940 - 945
DOI: 10.1126/science.7638616
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Articles

Science, Vol 269, Issue 5226, 940-945
Copyright © 1995 by American Association for the Advancement of Science

articles

Control of electron transfer between the L- and M-sides of photosynthetic reaction centers

BA Heller, D Holten, and C Kirmaier

Department of Chemistry, Washington University, St Louis, MO 63130, USA.

An aspartic acid residue has been introduced near ring V of the L-side accessory bacteriochlorophyll (BCHlL) or the photosynthetic reaction center in a rhodobacter capsulatus mutant in which a His also replaces Leu 212 on the M-polypeptide. The initial stage of charge separation in the G(M201)D/L(M212)H double mutant yields approximately 70 percent electron transfer to the L-side cofactors, approximately 15 percent rapid deactivation to the ground state, and approximately 15 percent electron transfer to the so-called inactive M-side bacteriopheophytin (BPhM). It is suggested here that the Asp introduced at M201 modulates the reduction potential of BCHlL, thereby changing the energetics of charge separation. The results demonstrate that an individual amino acid residue can, through its influence on the free energies of the charge-separated states, effectively dictate the balance between the forward electron transfer reactions on the L-side of the RC, the charge-recombination processes, and electron transfer to the M-side chromophores.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Strong Effects of an Individual Water Molecule on the Rate of Light-driven Charge Separation in the Rhodobacter sphaeroides Reaction Center.
J. A. Potter, P. K. Fyfe, D. Frolov, M. C. Wakeham, R. van Grondelle, B. Robert, and M. R. Jones (2005)
J. Biol. Chem. 280, 27155-27164
   Abstract »    Full Text »    PDF »
Interactions between lipids and bacterial reaction centers determined by protein crystallography.
A. Camara-Artigas, D. Brune, and J. P. Allen (2002)
PNAS 99, 11055-11060
   Abstract »    Full Text »    PDF »
Ab initio calculation of electronic coupling in the photosynthetic reaction center.
L. Y. Zhang and R. A. Friesner (1998)
PNAS 95, 13603-13605
   Abstract »    Full Text »    PDF »


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