Alexander O. Goushcha

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A model for light-induced charge separation in a donor-acceptor system of the reaction center of photosynthetic bacteria is described. This description is predicated on a self-regulation of the flow of photo-activated electrons due to self-consistent, slow structural rearrangements of the macromolecule. Effects of the interaction between the separated(More)
Experimental and theoretical results in support of nonlinear dynamic behavior of photosynthetic reaction centers under light-activated conditions are presented. Different conditions of light adaptation allow for preparation of reaction centers in either of two different conformational states. These states were detected both by short actinic flashes and by(More)
We describe the phenomenon of light-induced structural transformations in the reaction centers (RC) of photosynthetic bacteria which makes self-regulation of the RC charge separation efficiency possible. The nature of the effect is that the light-driven electron transfer (ET) between the RC redox-cofactors causes structural changes in the protein-cofactors(More)
Nonequilibrium dynamic effects in membrane-bound reaction centers (RCs) from photosynthetic bacteria are studied for the first time. We show that the accumulation of slow conformational changes triggered by charge-separation events in the RCs control system dynamics and depend on illumination conditions in a way similar to that for isolated RCs. The(More)
The quantum efficiency of silicon photodiodes and factors that might be responsible for the drop in quantum efficiency in the near-infrared spectral range were analyzed. It was shown that poor reflectivity from the rear surface of the die could account for a decrease in Si photodiode quantum efficiency in near-infrared spectral range by more than 20%. The(More)
Kinetics of electron transfer, following variation of actinic light intensity, for photosynthetic reaction centers (RCs) of purple bacteria (isolated and membrane-bound) were analyzed by measuring absorbance changes in the primary photoelectron donor absorption band at 865 nm. The bleaching of the primary photoelectron donor absorption band in RCs,(More)
The charge recombination lifetime of photosynthetic reaction centers (RCs) increases significantly upon lengthy illumination, revealing nonequilibrium structural transitions in the protein-cofactor system. This paper analyzes the charge recombination kinetics measured in isolated RCs following a systematic variation of actinic illumination times (pulses)(More)
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