Author
Vladimir A. Shuvalov
Other affiliations: Semenov Institute of Chemical Physics, University of Würzburg, Moscow State University ...read more
Bio: Vladimir A. Shuvalov is an academic researcher from Russian Academy of Sciences. The author has contributed to research in topics: Photosynthetic reaction centre & Rhodobacter sphaeroides. The author has an hindex of 44, co-authored 210 publications receiving 5407 citations. Previous affiliations of Vladimir A. Shuvalov include Semenov Institute of Chemical Physics & University of Würzburg.
Papers published on a yearly basis
Papers
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TL;DR: A reversible reduction of pheophytin in the primary light reaction of photosystem II in pea subchloroplast particles at redox potentials from -50 mV to -550 mV (when Q is in the reduced form) is demonstrated and is accompanied by a 2-3 fold decrease in the chlorophyll fluorescence yield.
373 citations
TL;DR: It is suggested that the photoreduction of P-760 occurs under the interaction of reduced cytochrome c with the reaction center state P+-890-P--760 which is induced by light, which appears to be a primary product of light reaction in the bacterial reaction centers.
157 citations
TL;DR: The efficiency of electrogenic phases depends first of all upon the value of the dielectric constant of the respective membrane regions rather than upon the distance between the redox groups involved.
Abstract: Electrogenic and redox events in the reaction-centre complexes from Rhodopseudomonas viridis have been studied. In contrast to the previous points of view it is shown that all the four hemes of the tightly bound cytochrome c have different Em values (-60, +20, +310 and +380 mV). The first three hemes reveal α absorption maxima at 554 nm, 552 nm and 556 nm respectively. The 380-mV heme displays a split α band with a maximum at 559 nm and a shoulder at 552 nm. Such a splitting is due to non-degenerated Qx and Qy transitions in the iron-porphyrin ring as demonstrated by magnetic circular dichroism spectra. Fast kinetic measurements show that, at redox potentials when only high-potential hemes c-559 and c-556 are reduced, heme c-559 appears to be the electron donor to P-960+ (τ= 0.32 μs) whereas heme c-556 serves to rereduce c-559 (τ= 2.5 μs). Upon reduction of the third heme (c-552), the P-960+ reduction rate increases twofold (τ= 0.17 μs) and all photoinduced redox events within the cytochrome appear to be complete in less than 1 μs after the flash. The following sequence of the redox centers is tentatively suggested: c-554, c-556, c-552, c-559, P-960.
To study electrogenesis, the reaction-centre complexes from Rps. viridis were incorporated into asolectin liposomes, and fast kinetics of laser flash-induced electric potential difference has been measured in proteoliposomes adsorbed on a phospholipid-impregnated film. The electrical difference induced by a single 15-ns flash was found to be as high as 100 mV. The photoelectric response has been found to involve four electrogenic stages associated with (I) QA reduction by P-960+ (II) reduction of P-960+ by heme c-559; (III) reduction of c-559 by c-556 and (IV) protonation of Q2−B. The relative contributions of stages I, II, III and IV are found to be equal to 70%, 15%, 5% and 10%, respectively, of the overall electrogenic process. At the same time, the first three respective distances along the axis normal to the membrane plane covered by electrons, calculated from X-ray data of Deisenhofer et al. [J. Mol. Biol. 180, 385–398 (1984)], are 22%, 18.5% and 26%. This indicates that the efficiency of electrogenic phases depends first of all upon the value of the dielectric constant of the respective membrane regions rather than upon the distance between the redox groups involved. The efficiency is higher, the deeper these groups are immersed in the membrane.
157 citations
TL;DR: The capability of bacteriochlorophyll (BChl) and bacteriopheophytin (Bph) to be reduced was demonstrated in vitro in 1951 and results have been interpreted as an indication of the charge separation between P and Bph during 10 ps.
157 citations
TL;DR: Shuvalov et al. as discussed by the authors measured the absorbance difference spectra at various delay times, and kinetics of absorbance changes induced by a 35 ps excitation pulse at 532 nm, measured of relatively intact Photosystem I particles from spinach containing about 70 chlorophyll a molecules per photoactive primary electron donor P-700.
138 citations
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TL;DR: In this article, the spectral characteristics and absorption coefficients of chlorophylls, pheophytins, and carotenoids were analyzed using a two-beam spectrophotometer.
Abstract: Publisher Summary This chapter presents detailed information on chlorophylls and carotenoids to give practical directions toward their quantitative isolation and determination in extracts from leaves, chloroplasts, thylakoid particles, and pigment proteins. The chapter focuses on the spectral characteristics and absorption coefficients of chlorophylls, pheophytins, and carotenoids, which are the basis for establishing equations to quantitatively determine them. Therefore, the specific absorption coefficients of the pigments are re-evaluated. This is achieved by using a two-beam spectrophotometer of the new generation, which allows programmed automatic recording and printing out of the proper wavelengths and absorbancy values. Several procedures have been developed for the separation of the photosynthetic pigments, including column (CC), paper (PC), and thin-layer chromatography (TLC) and high-pressure liquid chromatography (HPLC). All chloroplast carotenoids exhibit a typical absorption spectrum that is characterized by three absorption maxima (violaxanthin, neoxanthin) or two maxima with one shoulder (lutein and β-carotene) in the blue spectral region.
10,367 citations
TL;DR: In this paper, the electron transfer reactions between ions and molecules in solution have been the subject of considerable experimental study during the past three decades, including charge transfer, photoelectric emission spectra, chemiluminescent electron transfer, and electron transfer through frozen media.
7,155 citations
01 Jan 1991
TL;DR: Fluorescence as a Reaction Competing in the Deactivation of Excited Chlorophyll and the Origin of Fluorescence Emission.
Abstract: BIOPHYSICAL BASIS O F FLUORESCENCE EMISSION FROM CHLOROPLASTS . . . . .. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . 314 Fluorescence as a Reaction Competing in the Deactivation of Excited Chlorophyll . . . . . . . . . . ... . . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314 Lifetimes of Fluorescence . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . 317 Origin of Fluorescence Emission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 1 Fluorescence of PS 11 and PS I at Ambient and Low Temperatures . . . . . . . . . . . . . . . . . . . 323 FLUORESCENCE INDUCTION AND PS II HETEROGENEITy 325 Fluorescence Transient from Fo to FM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325 The FI Level and Inactive PS11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... .... . .. . . . .. . . . . . . . . . 326 Fluorescence Induction in High Ught .. . . . . . . . . 327 Rise in the Presence of DCMU and a/{3 Heterogeneity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327 FLUORESCENCE QUENCHING 329 Resolution of Quenching Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . ........ . .. . . . . . . . . . . . . . . 330 Mechanism of Energy·Dependent Quenching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3 1 Quenching Related t o State Transition . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . ......... . . .. .. . . . . . . . 334 Photoinhibitory Quenching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334 Further Quenching Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338 Physiological Aspects of Quenching . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . 338 CONCLUSIONS AND PERSPECTiVES 341
4,144 citations
TL;DR: The molecular structure of the photosynthetic reaction centre from Rhodopseudomonas viridis has been elucidated using X-ray crystallographic analysis and the first description of the high-resolution structure of an integral membrane protein is presented.
Abstract: The molecular structure of the photosynthetic reaction centre from Rhodopseudomonas viridis has been elucidated using X-ray crystallographic analysis. The central part of the complex consists of two subunits, L and M, each of which forms five membrane-spanning helices. We present the first description of the high-resolution structure of an integral membrane protein.
2,910 citations
TL;DR: In this paper, an atomic model of the prosthetic groups of the reaction center complex (4 bacteriochlorophyll b, 2 bacteriopheophytin b, 1 non-heme iron, 1 menaquinone, 4 heme groups) was built.
1,737 citations