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Modeling Charge Transfer in Oxidized Bacterial Antenna Complexes

Kolbasov, Dmitri and Srivatsan, Nagarajan and Ponomarenko, Nina and Jäger, Martin and Norris, James R., Jr. (2003) Modeling Charge Transfer in Oxidized Bacterial Antenna Complexes. Journal of Physical Chemistry B, 107 (10). pp. 2386-2393. ISSN 1520-6106. doi:10.1021/jp0265079.

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Bacterial light harvesting complexes type 1, LH1, probably contain a circular array of about 32 bacteriochlorophyll (BChl) pigments at a center-to-center distance of about 1 nm. Upon treatment with potassium ferricyanide, some of the BChls are reversibly oxidized, thus forming holes. The measured electron paramagnetic resonance (EPR) spectra of oxidized, detergent-isolated LH1 complexes from Rhodobacter sphaeroides and membrane-bound LH1 complexes from Blastochloris (formerly Rhodoseudomonas) viridis at 300 K have the width of 0.45 and 0.35 mT, respectively. This line width is independent of the fraction of the pigments oxidized, at least in the range of 3−30%. The EPR spectra of LH1 are 3−4 times as narrow as those of the monomer BChl cation, which is the evidence for the spin diffusion. The diffusion of holes in LH1 is simulated including electron transfer, mutual spin−spin repulsion, and spin exchange. A method for calculating the EPR spectrum from the simulated trajectories is described providing an opportunity to calculate the EPR spectrum of interacting, moving charges in a highly confined region. The observed spectral line width corresponds to an electron transfer rate constant in the range of 10^8−10^9 s^(-1). The calculated EPR line width weakly depends on the fraction of pigments oxidized in the range of 0−0.40 assuming strong Heisenberg spin exchange accompanied by electron transfer.

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Additional Information:© 2003 American Chemical Society. Received 11 July 2002. Published online 14 February 2003. Published in print 1 March 2003. We gratefully acknowledge support from the U. S. Department of Energy, Office of Basic Energy Sciences, and Division of Chemical Sciences Contract DE-FG02-96ER14675.
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Department of Energy (DOE)DE-FG02-96ER14675
Issue or Number:10
Record Number:CaltechAUTHORS:20170616-150429969
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Official Citation:Modeling Charge Transfer in Oxidized Bacterial Antenna Complexes Dmitri Kolbasov, Nagarajan Srivatsan, Nina Ponomarenko, Martin Jäger, and James R. Norris, Jr. The Journal of Physical Chemistry B 2003 107 (10), 2386-2393 DOI: 10.1021/jp0265079
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78302
Deposited By: Ruth Sustaita
Deposited On:16 Jun 2017 22:16
Last Modified:15 Nov 2021 17:38

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