REVIEW: Mechanisms of Excitation Trapping in Reaction Centers of Purple Bacteria

A. Yu. Borisov

Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia; fax: (095) 939-3181; E-mail: borissov@genebee.msu.su

Received March 27, 2002; Revision received July 3, 2002

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The contradiction between two groups of experimental data, which fails to be resolved within the framework of the widely accepted model of excitation migration and trapping (at least in case of purple bacteria), is discussed in the introduction to this review. Three directions of studies intended to resolve this conflict are reviewed in the three further sections: II. Exciton models; III. Water-polarization (water-latch) mechanism of excitation trapping; IV. Quantum-mechanical models. The maximum efficiency of these models in resolving the contradiction mentioned above was assessed. The advantages and disadvantages of the mechanisms described in sections II, III, and IV are discussed in the last section of this review. It is concluded that none of these mechanisms taken alone is able to solve this problem. Therefore, the fundamental problem of the primary excitation conversion in reaction centers remains unsolved and requires additional experimental research.

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KEY WORDS: purple bacteria, reaction center, electronic excitation energy migration and trapping

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