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Effect of Dipyridamole on Membrane Energization and Energy Transfer in Chromatophores of Rba. sphaeroides

Peter P. Knox1,a*, Eugene P. Lukashev1, Boris N. Korvatovskii1, Nuranija Kh. Seifullina1, Sergey N. Goryachev1, Elvin S. Allakhverdiev2, and Vladimir Z. Paschenko1

1Faculty of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia

2Russian National Medical Research Center of Cardiology, 121552 Moscow, Russia

* To whom correspondence should be addressed.

Received June 7, 2022; Revised August 24, 2022; Accepted August 24, 2022
Effect of dipyridamole (DIP) at concentrations up to 1 mM on fluorescent characteristics of light-harvesting complexes LH2 and LH1, as well as on conditions of photosynthetic electron transport chain in the bacterial chromatophores of Rba. sphaeroides was investigated. DIP was found to affect efficiency of energy transfer from the light-harvesting complex LH2 to the LH1–reaction center core complex and to produce the long-wavelength (“red”) shift of the absorption band of light-harvesting bacteriochlorophyll molecules in the IR spectral region at 840-900 nm. This shift is associated with the membrane transition to the energized state. It was shown that DIP is able to reduce the photooxidized bacteriochlorophyll of the reaction center, which accelerated electron flow along the electron transport chain, thereby stimulating generation of the transmembrane potential on the chromatophore membrane. The results are important for clarifying possible mechanisms of DIP influence on the activity of membrane-bound functional proteins. In particular, they might be significant for interpreting numerous therapeutic effects of DIP.
KEY WORDS: chromatophores, membrane energization, energy transfer, dipyridamole

DOI: 10.1134/S0006297922100078