Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.
Science Policy Alerts

Site Tools

  • AAAS
  • Subscribe
  • Feedback

Site Search

Search Advanced

Science 6 May 1994:
Vol. 264. no. 5160, pp. 810 - 816
DOI: 10.1126/science.264.5160.810
Prev | Table of Contents | Next

Articles

Dielectric Asymmetry in the Photosynthetic Reaction Center

Martin A. Steffen 1, Kaiqin Lao 1, and Steven G. Boxer 1

1 Department of Chemistry, Stanford University, Stanford, CA 94305-5080, USA.

Although the three-dimensional structure of the bacterial photosynthetic reaction center (RC) reveals a high level of structural symmetry, with two nearly equivalent potential electron transfer pathways, the RC is functionally asymmetric: Electron transfer occurs along only one of the two possible pathways. In order to determine the origins of this symmetry breaking, the internal electric field present in the RC when charge is separated onto structurally characterized sites was probed by using absorption band shifts of the chromophores within the RC. The sensitivity of each probe chromophore to an electric field was calibrated by measuring the Stark effect spectrum, the change in absorption due to an externally applied electric field. A quantitative comparison of the observed absorption band shifts and those predicted from vacuum electrostatics gives information on the effective dielectric constant of the protein complex. These results reveal a significant asymmetry in the effective dielectric strength of the protein complex along the two potential electron transfer pathways, with a substantially higher dielectric strength along the functional pathway. This dielectric asymmetry could be a dominant factor in determining the functional asymmetry of electron transfer in the RC.

Submitted on August 30, 1993
Accepted on April 7, 1994


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
How Proteins Trigger Excitation Energy Transfer in the FMO Complex of Green Sulfur Bacteria.
J. Adolphs and T. Renger (2006)
Biophys. J. 91, 2778-2797
   Abstract »    Full Text »    PDF »
Function of Redox-Active Tyrosine in Photosystem II.
H. Ishikita and E.-W. Knapp (2006)
Biophys. J. 90, 3886-3896
   Abstract »    Full Text »    PDF »
Proton Binding to Proteins: A Free-Energy Component Analysis Using a Dielectric Continuum Model.
G. Archontis and T. Simonson (2005)
Biophys. J. 88, 3888-3904
   Abstract »    Full Text »    PDF »
Theory of Optical Spectra of Photosystem II Reaction Centers: Location of the Triplet State and the Identity of the Primary Electron Donor.
G. Raszewski, W. Saenger, and T. Renger (2005)
Biophys. J. 88, 986-998
   Abstract »    Full Text »    PDF »
Electrochromic Shift of Chlorophyll Absorption in Photosystem I from Synechocystis sp. PCC 6803: A Probe of Optical and Dielectric Properties around the Secondary Electron Acceptor.
N. Dashdorj, W. Xu, P. Martinsson, P. R. Chitnis, and S. Savikhin (2004)
Biophys. J. 86, 3121-3130
   Abstract »    Full Text »    PDF »
Ligand dynamics in a protein internal cavity.
J. M. Kriegl, K. Nienhaus, P. Deng, J. Fuchs, and G. U. Nienhaus (2003)
PNAS 100, 7069-7074
   Abstract »    Full Text »    PDF »
Probing Protein Electrostatics with a Synthetic Fluorescent Amino Acid.
B. E. Cohen, T. B. McAnaney, E. S. Park, Y. N. Jan, S. G. Boxer, and L. Y. Jan (2002)
Science 296, 1700-1703
   Abstract »    Full Text »    PDF »
Gaussian fluctuations and linear response in an electron transfer protein.
T. Simonson (2002)
PNAS 99, 6544-6549
   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 »


ADVERTISEMENT
Click Me!

ADVERTISEMENT
Click Me!

To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)