Biopolymers and cell. 2010; 26 (4): 286 - 294
Deceleration of the electron transfer reaction in the photosynthetic reaction centre as a manifestation of its structure fluctuations
V. N. Kharkyanen1, Yu. M. Barabash1, N. M. Berezetskaya1, M. V. Olenchuk1, P. P. Knox2, L. N. Christophorov1, 3
1Institute of Semiconductor Physics NAS of Ukraine, 46, prospect Nauki, Kyiv, Ukraine, 03039
2 Lomonosov Moscow State University, GSP-1, Leninskie Gory, Moscow, Russian Federation, 119991
3Bogolyubov Institute for Theoretical Physics NAS of Ukraine, 14-b, Metrolohichna Str., Kyiv, Ukraine, 03680
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.