Biopolym. Cell. 2010; 26(4):286-294.
http://dx.doi.org/10.7124/bc.000161
Molecular Biophysics
Deceleration of the electron transfer reaction in the photosynthetic reaction centre as a manifestation of its structure fluctuations
1Kharkyanen V. N., 1Barabash Yu. M., 1Berezetskaya N. M., 1Olenchuk M. V., 2Knox P. P., 3Christophorov L. N.
  1. Institute of Physics, NAS of Ukraine
    46, Prospect Nauki, Kyiv, Ukraine, 03028
  2. M. V. Lomonosov Moscow State University
    Leninskie Gory, Moscow, Russian Federation, 119991
  3. Bogolyubov Institute for Theoretical Physics, NAS of Ukraine
    14 b Metrologichna Str., Kyiv, Ukraine, 03680

Abstract

Aim. To extract information on the nature of protein structural relaxation from the kinetics of electron transfer reaction in the photosynthetic reaction centre (RC). Methods. The kinetic curves obtained by absorption spectroscopy are processed by a maximum entropy method to get the spectrum of relaxation times. Results. A series of distinctive peaks of this spectrum in the interval from 0.1 s to hundreds of seconds is revealed. With the time of exposure of the sample to actinic light increasing, the positions of the peak maxima grow linearly. Conclusions. Theoretical analysis of these results reveals the formation of several structural states of the RC protein. Remarkably, in each of these states the slow reaction kinetics follow the same fractional power law that reflects the glass-like properties of the protein.
Keywords: protein structure relaxation, nonexponential kinetics, time-dependent reaction barrier, primary reactions of photosynthesis
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