Mechanism by which a single water molecule affects primary charge separation kinetics in a bacterial photosynthetic reaction center of Rhodobacter sphaeroides

Ivashin, N. V.; Shchupak, E. E.

doi:10.1134/s0030400x1209007x

Cited by 7 publications

(9 citation statements)

References 51 publications

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“…Because this occurred only in M3 , we conclude that it was the result of structural changes associated with the GM203L mutation, the main effect of which is the removal of a water molecule directly linking P B and B A 29 . Various experimental and theoretical simulations have studied the role of this water, showing that its presence increased the coupling between P and B A 22 , reduced the energy of by ~600 cm −1 , and stabilized 40,41 . Our results consolidate previous ideas by showing that increased backward ET considerably reduced the stability of .…”

Section: Resultsmentioning

confidence: 99%

“…Previous experiments have found that the 30−35 cm −1 vibrational mode disappears when the water molecule between P B and B A was removed 3,31,41 . Theoretical studies identified this mode to be a proton displacement of this water that stabilizes by reducing the driving force for charge recombination 22,40 . From 2D-EAS analysis, we found that the backward reaction of ET was much more effective in M3 than in M1 or M2 .…”

Section: Resultsmentioning

confidence: 99%

“…In the second step, , stabilization of the formed is another factor that influences the overall primary ET efficiency: is stabilized by a proton displacement involving a vibrational mode of 30−35 cm −1 22,40 , without which charge recombination would occur. We found that this vibrational coherence was as long-lived as ~2 ps, and its disappearance correlated with the enhanced backward reaction, i.e., more charge recombination.…”

Section: Discussionmentioning

confidence: 99%

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Both electronic and vibrational coherences are involved in primary electron transfer in bacterial reaction center

Ma¹,

Romero²,

Jones

et al. 2019

Nat Commun

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Understanding the mechanism behind the near-unity efficiency of primary electron transfer in reaction centers is essential for designing performance-enhanced artificial solar conversion systems to fulfill mankind’s growing demands for energy. One of the most important challenges is distinguishing electronic and vibrational coherence and establishing their respective roles during charge separation. In this work we apply two-dimensional electronic spectroscopy to three structurally-modified reaction centers from the purple bacterium Rhodobacter sphaeroides with different primary electron transfer rates. By comparing dynamics and quantum beats, we reveal that an electronic coherence with dephasing lifetime of ~190 fs connects the initial excited state, P*, and the charge-transfer intermediate ; this step is associated with a long-lived quasi-resonant vibrational coherence; and another vibrational coherence is associated with stabilizing the primary photoproduct, . The results show that both electronic and vibrational coherences are involved in primary electron transfer process and they correlate with the super-high efficiency.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Both electronic and vibrational coherences are involved in primary electron transfer in bacterial reaction center

Ma¹,

Romero²,

Jones

et al. 2019

Nat Commun

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“…According to the recommendations of [37], the molecular energy in the ground and redox states was calculated by the DFT/B3LYP method using the extended basis set 6 311++g(2d, 2p). This approach allowed us to find the E ox potentials of porphyrins and E red of O 2 in good agreement with experimental data, as well as in our previous works [38,39]. The geometry of molecules and the vectors of nor mal vibrations were visualized with Molekel 4.3 [40] and GaussView [41] programs.…”

Section: Methodsmentioning

confidence: 70%

“…Calculation of ΔG ET was per formed taking into account the solvation energy (PCM method), thermal corrections for enthalpy and entropy, and corrections for zero point vibrations [37,38]. According to the recommendations of [37], the molecular energy in the ground and redox states was calculated by the DFT/B3LYP method using the extended basis set 6 311++g(2d, 2p).…”

Section: Methodsmentioning

confidence: 99%

The effect of the structure and conformational dynamics on quenching of triplet states of porphyrins and their chemical dimers by molecular oxygen and on singlet oxygen generation

2015

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Quantum chemical calculations are performed to analyze the factors affecting rate constant k T of quenching of the lowest triplet state by molecular oxygen and quantum yield γ Δ of singlet oxygen generation in chemical dimers of porphyrins bound by phenyl spacers at one of the meso positions (OEP) 2 Ph, (TPP) 2 , and their Zn complexes. It is established that, for both types of dimers, the triplet excitation is localized on one of the mac rocycles. The steric hindrance of macrocycles at the site of the phenyl ring of (OEP) 2 Ph, (ZnOEP) 2 Ph, and their monomeric analogues OEP Ph and ZnOEP Ph facilitates its rotation by 90° in the triplet state. The lowest triplet state energy in this (U) conformation is lower than 7800 cm -1 , which makes impossible elec tronic excitation energy transfer to molecular oxygen. The potential barrier of transformation to the U con formation is considerably lower for dimers than for monomers. Because of this, the rate of conformational transformations for dimers is higher and some of the (OEP) 2 Ph and (ZnOEP) 2 Ph molecules have time to transform into the new U conformation before diffusion collision with O 2 molecules in solution. This leads to a noticeable decrease in γ Δ in accordance with experimental data. It is shown that the behavior of k T in the series of the studied dimers, their monomeric analogues, and relative compounds corresponds to the model of dipole-dipole electronic excitation energy transfer 1 ( 3 M⋅⋅⋅ ) → 1 ( 1 M 0 ⋅⋅⋅ 1 Δ g ) in collisional complexes.

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Dynamics of diverse coherences in primary charge separation of bacterial reaction center at 77 K revealed by wavelet analysis

Romero

Jones

et al. 2021

Photosynth Res

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Mechanism by which a single water molecule affects primary charge separation kinetics in a bacterial photosynthetic reaction center of Rhodobacter sphaeroides

Cited by 7 publications

References 51 publications

Both electronic and vibrational coherences are involved in primary electron transfer in bacterial reaction center

Both electronic and vibrational coherences are involved in primary electron transfer in bacterial reaction center

The effect of the structure and conformational dynamics on quenching of triplet states of porphyrins and their chemical dimers by molecular oxygen and on singlet oxygen generation

Dynamics of diverse coherences in primary charge separation of bacterial reaction center at 77 K revealed by wavelet analysis

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