Protein dynamics control of electron transfer in reaction centers from<i>Rps. viridis</i>

Medvedev, Emile S.; Kotelnikov, A. I.; Goryachev, N. S.; Psikha, B. L.; Ortega, José M.; Stuchebrukhov, Alexei A.

doi:10.1080/08927020600880802

Cited by 12 publications

(52 citation statements)

References 37 publications

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“…viridis. 1 The data obtained now for two bacteria allow one to speculate about the possible nature of the protein relaxation dynamics involved in regulation of electron transfer in these systems. We believe one of the main contributors to such dynamics is the process of breaking and making hydrogen bonds of internal water molecules in the protein and the protein structure itself.…”

Section: Discussionmentioning

confidence: 95%

“…A possible reason for the slow ET reaction between c-559 and P + in a fraction of the enzymes was proposed 1 to be due to partial protonation of an unknown group located in a vicinity of c-559, which either modulates redox potential of c-559 or forms H bonds with a water molecule(s) and hinders the dipole reorientations in the protein, and thus hinders the ET reaction. 1 Such a possibility is further examined in the present study below. Both the slow population and the c-559-oxidized fractions of the enzyme are contributing to Q A − to P + back reaction, which forms the millisecond (very slow, VS) phase of the observed kinetics.…”

Section: Resultsmentioning

confidence: 99%

“…The equilibrium value 〈X〉 (taken to be zero in the reagents state) is determined by the minimum of the free energy profile of X; in the vicinity of its minimum, the free energy profile V(X) is assumed to be harmonic. The distribution P(X;t) obeys the classical diffusionreaction equation, (1) where V(X) = (1/2)X 2 is the harmonic (free energy) potential along the diffusive X coordinate in the reagents state, and τ is the relaxation time of X, one of the key parameters of the model. The ET reaction can occur at any value X; however, the reaction rate strongly depends on the conformational state of the protein X.…”

Section: Modelmentioning

confidence: 99%

“…Theoretical analysis of the microsecond reaction of electron transfer from proximal heme c-559 to the oxidized bacteriochlorophyll dimer in the reaction center from the photosynthetic bacterium Rps. viridis has been described in our previous paper of this series, 1 where we developed an approach based on the diffusion-reaction equation. [17][18][19][20][21][22][23][24][25][26][27] This approach enabled us to explore the protein dynamics on the microsecond time scale, which is intermediate between the time scales studied in the above-cited works.…”

Section: Introductionmentioning

confidence: 99%

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Protein Dynamics Control of Electron Transfer in Photosynthetic Reaction Centers from Rps. Sulfoviridis

et al. 2008

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In the cycle of photosynthetic reaction centers, the initially oxidized special pair of bacteriochlorophyll molecules is subsequently reduced by an electron transferred over a chain of four hemes of the complex. Here, we examine the kinetics of electron transfer between the proximal heme c-559 of the chain and the oxidized special pair in the reaction center from Rps. sulfoviridis in the range of temperatures from 294 to 40 K. The experimental data were obtained for three redox states of the reaction center, in which one, two, or three nearest hemes of the chain are reduced prior to special pair oxidation. The experimental kinetic data are analyzed in terms of a Sumi-Marcus-type model developed in our previous paper,1 in which similar measurements were reported on the reaction centers from Rps. viridis. The model allows us to establish a connection between the observed nonexponential electron-transfer kinetics and the local structural relaxation dynamics of the reaction center protein on the microsecond time scale. The activation energy for relaxation dynamics of the protein medium has been found to be around 0.1 eV for all three redox states, which is in contrast to a value around 0.4-0.6 eV in Rps. viridis.1 The possible nature of the difference between the reaction centers from Rps. viridis and Rps. sulfoviridis, which are believed to be very similar, is discussed. The role of the protein glass transition at low temperatures and that of internal water molecules in the process are analyzed.

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Section: Discussionmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Section: Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Protein Dynamics Control of Electron Transfer in Photosynthetic Reaction Centers from Rps. Sulfoviridis

et al. 2008

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“…This distribution should be considered as changing in a self-consistent manner together with the progress of the reaction, as in the Sumi-Marcus type models of electron transfer, see e.g. Refs 103,104…”

Section: Kinetics Of Electron Transfer Reactions Coupled To Protonmentioning

confidence: 99%

Theory of Coupled Electron and Proton Transfer Reactions

2010

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Structural and dynamic aspects of electron transfer in proteins — highly organized natural nanostructures

2011

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Protein dynamics control of electron transfer in reaction centers fromRps. viridis

Cited by 12 publications

References 37 publications

Protein Dynamics Control of Electron Transfer in Photosynthetic Reaction Centers from Rps. Sulfoviridis

Protein Dynamics Control of Electron Transfer in Photosynthetic Reaction Centers from Rps. Sulfoviridis

Theory of Coupled Electron and Proton Transfer Reactions

Structural and dynamic aspects of electron transfer in proteins — highly organized natural nanostructures

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