Primary charge separation within the structurally symmetric tetrameric Chl2APAPBChl2B chlorophyll exciplex in photosystem I

Cherepanov, Dmitry A.; Шелаев, И. В.; Гостев, Ф. Е.; Petrova, Anastasia; Aybush, Arseniy V.; Надточенко, В. А.; Xu, Wu; Golbeck, John H.; Semenov, Alexey Yu.

doi:10.1016/j.jphotobiol.2021.112154

Cited by 23 publications

(30 citation statements)

References 72 publications

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“…Compared to WT PS I, the spectrograms of absorption changes in the altered PS I variants reveal a more extensive process of energy migration from the excited antenna to the RC at the time range of 1-2 ps, which is consistent with the lower yields of the charge transfer state P 700 + Chl 2 − directly generated in the altered PS I variants [35].…”

Section: Continual Multi-exponential Analysis Of Absorption Changessupporting

confidence: 67%

“…3, 4, 5, red lines). This phenomenon was explained in a recent companion work by a decreased yield of the primary radical ion pairs P 700 + Chl 2A − or P 700 + Chl 2B − as a consequence of lowering the redox potential of the respective Chl 2A or Chl 2B monomers due to removal of the -NH 2 groups, which directly contact the Chl 2A or Chl 2B macrocycles by hydrogen atoms in the wild-type structure [35]. Examination of the data obtained by earlier femtosecond time-resolved absorption and fluorescence spectroscopies gave grounds to conclude that the similar amino acid substitutions lead to blocking of electron transfer in the modified branch of redox cofactors, which was not compensated by electron transfer in the alternative non-modified branch [29].…”

Section: Transient Absorption Changes Of Photosystem I Variantsmentioning

confidence: 96%

“…The appearance of a bleach at 690 nm was previously attributed to an ultrafast (< 100 fs) reduction of the primary electron acceptor A 0 treated as excitonically coupled dimers Chl 2A -Chl 3A and Chl 2B -Chl 3B [20] in that fraction of PS I complexes in which the special pair P 700 was directly excited in the far-red spectral region [12,13]. However, the minimum at 690 nm observed at the shortest delay is now known to represent the reduced accessory Chl 2A and Chl 2B monomers [35], while the electron equilibration between Chl 2A /Chl 2B and Chl 3A /Chl 3B proceeds at 2-5 ps [10,16,44]. The excited-state absorption maxima in the region of 650-670 nm may belong to both the excited state of Chl a [45,46] and to the A 0 anion [5].…”

Section: Transient Absorption Changes Of Photosystem I Variantsmentioning

confidence: 99%

“…Figure 7 shows also the transient spectra of the P 700 The differences in the S 0 (λ) spectra may be only partially explained by a varying contribution of the P 700 + Chl 2 − chargetransfer state generated in the symmetric Chl 2A P A P B Chl 2B exciplex upon excitation. This contribution, denoted as the parameter α, was calculated by the principal component analysis of the spectra [35] The P 700 variants (green). However, even though the P 700 + Chl − contribution was minimal in the PsaB-N582H variant (α = 0.15), the Soret bleach amplitude of this complex (f, blue) was greater than that of the WT PS I.…”

Section: Quantum Yield Of the Charge Separation Reactionsmentioning

confidence: 99%

“…In a previous paper, we analyzed the primary charge separation in the same PsaA-N600M/H/L and PsaBN582M/H/L variants from cyanobacteria Synechocystis sp. PCC 6803 by focusing on the earliest events in charge separation [35]. We showed that the primary charge separation (lifetime < 100 fs) proceeds within a symmetric tetrameric exciplex in which the excited state (Chl 2A P A P B Chl 2B )* is mixed with charge-transfer states P 700 + Chl 2A − and P 700 + Chl 2B − .…”

Section: Introductionmentioning

confidence: 99%

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Symmetry breaking in photosystem I: ultrafast optical studies of variants near the accessory chlorophylls in the A- and B-branches of electron transfer cofactors

Cherepanov

Шелаев

Гостев

et al. 2021

Photochem Photobiol Sci

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Femtosecond absorption spectroscopy of Photosystem I (PS I) complexes from the cyanobacterium Synechocystis sp. PCC 6803 was carried out on three pairs of complementary amino acid substitutions located near the second pair of chlorophyll molecules Chl 2A and Chl 2B (also termed A -1A and A -1B ). The absorption dynamics at delays of 0.1-500 ps were analyzed by decomposition into discrete decay-associated spectra and continuously distributed exponential components. The multiexponential deconvolution of the absorption changes revealed that the electron transfer reactions in the PsaA-N600M, PsaA-N600H, and PsaA-N600L variants near the B-branch of cofactors are similar to those of the wild type, while the PsaB-N582M, PsaB-N582H, and PsaB-N582L variants near the A-branch of cofactors cause significant alterations of the photochemical processes, making them heterogeneous and poorly described by a discrete exponential kinetic model. A redistribution of the unpaired electron between the second and the third monomers Chl 2A /Chl 2B and Chl 3A /Chl 3B was identified in the time range of 9-20 ps, and the subsequent reduction of A 1 was identified in the time range of 24-70 ps. In the PsaA-N600L and PsaB-N582H/L variants, the reduction of A 1 occurred with a decreased quantum yield of charge separation. The decreased quantum yield correlates with a slowing of the phylloquinone A 0 → A 1 reduction, but not with the initial transient spectra measured at the shortest time delay. The results support a branch competition model, where the electron is sheared between Chl 2A -Chl 3A and Chl 2B -Chl 3B cofactors before its transfer to phylloquinone in either A 1A or A 1B sites.

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Section: Continual Multi-exponential Analysis Of Absorption Changessupporting

confidence: 67%

Section: Transient Absorption Changes Of Photosystem I Variantsmentioning

confidence: 96%

Section: Transient Absorption Changes Of Photosystem I Variantsmentioning

confidence: 99%

Section: Quantum Yield Of the Charge Separation Reactionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Symmetry breaking in photosystem I: ultrafast optical studies of variants near the accessory chlorophylls in the A- and B-branches of electron transfer cofactors

Cherepanov

Шелаев

Гостев

et al. 2021

Photochem Photobiol Sci

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A Symmetry‐Broken Charge‐Separated State in the Marcus Inverted Region

Sebastian

Hariharan

2023

Angewandte Chemie

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We report a long‐lived charge‐separated state in a chromophoric pair (DC‐PDI2) that uniquely integrates the advantages of fundamental processes of photosynthetic reaction centers: i) Symmetry‐breaking charge‐separation (SB‐CS) and ii) Marcus‐inverted‐region dependence. The near‐orthogonal bichromophoric DC‐PDI2 manifests an ultrafast evolution of the SB‐CS state with a time constant of τSB-CS ${{\tau }_{{\rm S}{\rm B}-{\rm C}{\rm S}}}$ =0.35±0.02 ps and a slow charge recombination (CR) kinetics with τCR ${{\tau }_{{\rm C}{\rm R}}}$ =4.09±0.01 ns in ACN. The rate constant of CR of DC‐PDI2 is 11 686 times slower than SB‐CS in ACN, as the CR of the PDI radical ion‐pair occurs in the deep inverted region of the Marcus parabola ( -ΔGCR ${{-{\rm \Delta }G}_{{\rm C}{\rm R}}}$ >λ). In contrast, an analogous benzyloxy (BnO)‐substituted DC‐BPDI2 showcases a ≈10‐fold accelerated CR kinetics with τnormalCnormalR/τnormalSnormalB-normalCnormalS ${{\tau }_{{\rm C}{\rm R}}/{\tau }_{{\rm S}{\rm B}-{\rm C}{\rm S}}}$ lowering to ≈1536 in ACN, by virtue of a decreased CR driving force. The present investigation demonstrates a control of molecular engineering to tune the energetics and kinetics of the SB‐CS material, which is essential for next‐generation optoelectronic devices.

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