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Science 22 February 1991:
Vol. 251. no. 4996, pp. 922 - 927
DOI: 10.1126/science.2000491
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Articles

Science, Vol 251, Issue 4996, 922-927
Copyright © 1991 by American Association for the Advancement of Science

articles

Charge separation in a reaction center incorporating bacteriochlorophyll for photoactive bacteriopheophytin

C Kirmaier, D Gaul, R DeBey, D Holten, and CC Schenck

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

Site-directed mutagenic replacement of M subunit Leu214 by His in the photosynthetic reaction center (RC) from Rhodobacter sphaeroides results in incorporation of a bacteriochlorophyll molecule (BChl) in place of the native bacteriopheophytin (BPh) electron acceptor. Evidence supporting this conclusion includes the ground-state absorption spectrum of the (M)L214H mutant, pigment and metal analyses, and time-resolved optical experiments. The genetically modified RC supports transmembrane charge separation from the photoexcited BChl dimer to the primary quinone through the new BChl molecule, but with a reduced quantum yield of 60 percent (compared to 100 percent in wild-type RCs). These results have important implications for the mechanism of charge separation in the RC, and rationalize the choice of (bacterio)pheophytins as electron acceptors in a variety of photosynthetic systems.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Electron transfer in the Rhodobacter sphaeroides reaction center assembled with zinc bacteriochlorophyll.
S. Lin, P. R. Jaschke, H. Wang, M. Paddock, A. Tufts, J. P. Allen, F. I. Rosell, A. G. Mauk, N. W. Woodbury, and J. T. Beatty (2009)
PNAS 106, 8537-8542
   Abstract »    Full Text »    PDF »
Control of electron transfer between the L- and M-sides of photosynthetic reaction centers.
B. Heller, D Holten, and C Kirmaier (1995)
Science 269, 940-945
   Abstract »    PDF »
Dielectric Asymmetry in the Photosynthetic Reaction Center.
M. A. Steffen, K. Lao, and S. G. Boxer (1994)
Science 264, 810-816
   Abstract »    PDF »


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