Vladimir P. Shinkarev

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The xanthophyll cycle-dependent dissipation of excitation energy in higher plants is one of the most important regulatory and photoprotective mechanisms in photosynthesis. Using parallel time-resolved and pulse-amplitude modulation fluorometry, we studied the influence of the intrathylakoid pH and the xanthophyll cycle carotenoids on the PSII chlorophyll(More)
Flash-induced oxygen evolution in the thylakoids of plants and algae exhibits damped oscillations with period four. These are well described by the S-state model of Kok et al. [Kok, B., Forbush, B. & McGloin, M. (1970) Photochem. Photobiol. 11, 457-475], with damping provided by empirical misses and double hits in the reaction center of photosystem II. Here(More)
Crystallographic structures of the bc1 complex from different sources have provided evidence that a movement of the Rieske iron-sulfur protein (ISP) extrinsic domain is essential for catalysis. This dynamic feature has opened up the question of what limits electron transfer, and several authors have suggested that movement of the ISP head, or gating of such(More)
Flash-induced oxygen evolution in higher plants, algae, and cyanobacteria exhibits damped period-four oscillations. To explain such oscillations, Kok suggested a simple phenomenological S-state model, in which damping is due to empirical misses and double-hits. Here we developed an analytical solution for the extended Kok model that includes misses,(More)
The cytochrome bc(1) complex is the central enzyme of respiratory and photosynthetic electron-transfer chains. It couples the redox work of quinol oxidation and cytochrome reduction to the generation of a proton gradient needed for ATP synthesis. When the quinone processing Q(i)- and Q(o)-sites of the complex are inhibited by both antimycin and myxothiazol,(More)
Since available structures of native bc(1) complexes show a vacant Q(o)-site, occupancy by substrate and product must be investigated by kinetic and spectroscopic approaches. In this brief review, we discuss recent advances using these approaches that throw new light on the mechanism. The rate-limiting reaction is the first electron transfer after formation(More)
Light activation of photosystem I (PS I) induces electron transfer from the excited primary electron donor P700 (a special pair of chlorophyll a/a' molecules) to three iron-sulfur clusters, F(X), F(A), and F(B) via acceptors A(0) (a monomeric chlorophyll a) and A(1) (phylloquinone). PS I complexes isolated from menA and menB mutants contain plastoquinone-9(More)
Photosystem II (PS II) of plants and cyanobacteria, which catalyzes the light-induced splitting of water and the release of oxygen, is the primary source of oxygen in the earth atmosphere. When activated by short light flashes, oxygen release in PS II occurs periodically with maxima after the third and the seventh flashes. Many other processes, including(More)
Following addition of myxothiazol to antimycin-treated chromatophores from Rhodobacter sphaeroides poised at an ambient redox potential (E(h)) of approximately 300 mV, the amplitude of the flash-induced cytochrome c(1) oxidation in the ms range increased, indicating a decrease in the availability of electrons from the immediate donor to c(1), the Rieske(More)
The kinetics of light-induced electron transfer in reaction centers (RCs) from the purple photosynthetic bacterium Rhodobacter sphaeroides were studied in the presence of the detergent lauryldimethylamine-N-oxide (LDAO). After the light-induced electron transfer from the primary donor (P) to the acceptor quinone complex, the dark re-reduction of P+ reflects(More)