The influence of electrostatic interactions and intramolecusar dynamics on electron transfer from the cytochrome suhunit to the cation - radical of the bacteriochlorophyll dimer in reaction centers from Rps. viridis

E. N. Frolov, V. I. Goldanskii, A. Birk, F. Parak

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13 Scopus citations

Abstract

Interheme electrostatic interaction can explain the acceleration of the electron transfer (ET) rate from the highest potential heme (C380) to the photooxidized bacteriochlorophyll dimer (P+) which takes place after the reduction of neighbouring heme(s) of the cytochrome subunit in the reaction center of Rps. viridis. The electrostatic interaction energies calculated for neighbouring hemes, 7.0 Å apart (edge-to-edge), and for two high potential hemes, 21.5 Å apart are found to be 0.1 10 eV and 0.040 eV respectively. The reorganisation energy of the C380-P+ transition of about 0.290±0.030 eV is calculated using the Marcus theory of electron tunneling. An empirical relation for the rate of ET is given. The low temperature restriction of the C380-P+ transition is caused by an energetic inhibition which originates from an opposite shifting of the energy levels of C380 and P+ due to the freezing of protein dynamics and protein-bound water mobility. The freezing of the protein dynamics is revealed by the Mossbauer effect and correlates with the efficiency of the ET.

Original languageEnglish
Pages (from-to)433-438
Number of pages6
JournalEuropean Biophysics Journal
Volume24
Issue number6
DOIs
StatePublished - 1996

Keywords

  • Cytochrome
  • Dynamics
  • Electron tunneling
  • Mossbauer spectroscopy
  • Reaction center

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