Analysis of absorption spectra of purple bacterial reaction centers in the near infrared region by higher order derivative spectroscopy

Mikhailyuk, I. K.; Knox, P. P.; Paschenko, V.Z.; Razjivin, A.P.; Lokstein, Heiko

doi:10.1016/j.bpc.2006.02.002

Cited by 12 publications

(13 citation statements)

References 40 publications

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“…sphaeroides, as mentioned above, are consistent with data shown in Figures 1 and 2 and left panels in Figures 3 and 4. Mikhailyuk et al 10 also concluded (via analysis of absorption spectra of Rba. sphaeroides by higher order derivative spectroscopy) that the P Y+ band must have a maximum near 810 nm.…”

Section: ■ Results and Discussionmentioning

confidence: 93%

“…Note that the upper exciton state of the special pair (for V PA/PB = 625 cm −1 ) is delocalized, as it is strongly mixed with the excited states of accessory BChls (B*), though it contributes mostly to the low-energy side of the B band, as often indicated in the literature. 10,15,17 That is, P A and P B also contribute to the second, third, and fourth exciton states. This is clearly visible in frame C of Figure 4, which illustrates the contributions from all pigments and the CT1 state.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…capsulatus that lacks the primary acceptor ubiquinone, suggested that the hidden upper exciton state of the special pair lies near 11900 cm −1 (∼840 nm), i.e., at significantly lower energy than previously suggested. 10,[14][15][16]24 Namely, these authors argued that using 2DES they directly resolved the P + * state of the special pair (P Y+ in our nomenclature used in this work), which based on their kinetics data rapidly decayed to the lower energy exciton state, P − * (=P Y− ), in 24 fs. 6 Comparison of the above-mentioned energies of the P Y− and P Y+ states is complicated, as the energy of the P Y− band is strongly temperature dependent; i.e., the P Y− band of Rba.…”

Section: ■ Introductionmentioning

confidence: 97%

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Mixed Upper Exciton State of the Special Pair in Bacterial Reaction Centers

2019

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Excitonic interactions between two closely separated bacteriochlorophyll a molecules (BChls) in the special pair of the reaction center (RC) of purple bacteria determine the positions and relative oscillator strengths of its two excitonic components. While the absorption of the lower excitonic band is well-defined, the position and the intensity of the upper excitonic band (PY+ ) are still under debate. Recent 77 K two-dimensional electronic spectroscopy data on Rba. capsulatus suggested that the PY+ component absorbs at ∼840 nm, i.e., at a significantly lower energy than previously suggested. In the present work, we argue that the PY+ state is mixed with the excited states of the accessory BChls (B*/P Y+) leading to excitons contributing to the 785–825 nm spectral region which is consistent with previously published data. This conclusion is based on hole-burning/linear dichroism data and modeling studies of the excitonic structure of the RC using a non-Markovian reduced density matrix approach.

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Section: ■ Results and Discussionmentioning

confidence: 93%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 97%

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Mixed Upper Exciton State of the Special Pair in Bacterial Reaction Centers

2019

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“…In contrast, as illustrated in Fig. 1 , pigment-proteins from organisms containing BChl a have very strong absorbance in the near infrared between 700 and 900 nm, and up to 1100 nm in organisms that contain BChl b (Mikhailyuk et al 2006 ). Thus, a possible modification of the design of the DSSC is to replace the synthetic dye with a photoactive pigment-protein such as a RC.…”

Section: Introductionmentioning

confidence: 99%

Modelling of the cathodic and anodic photocurrents from Rhodobacter sphaeroides reaction centres immobilized on titanium dioxide

et al. 2018

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As one of a number of new technologies for the harnessing of solar energy, there is interest in the development of photoelectrochemical cells based on reaction centres (RCs) from photosynthetic organisms such as the bacterium Rhodobacter (Rba.) sphaeroides. The cell architecture explored in this report is similar to that of a dye-sensitized solar cell but with delivery of electrons to a mesoporous layer of TiO2 by natural pigment-protein complexes rather than an artificial dye. Rba. sphaeroides RCs were bound to the deposited TiO2 via an engineered extramembrane peptide tag. Using TMPD (N,N,N′,N′-tetramethyl-p-phenylenediamine) as an electrolyte, these biohybrid photoactive electrodes produced an output that was the net product of cathodic and anodic photocurrents. To explain the observed photocurrents, a kinetic model is proposed that includes (1) an anodic current attributed to injection of electrons from the triplet state of the RC primary electron donor (PT) to the TiO2 conduction band, (2) a cathodic current attributed to reduction of the photooxidized RC primary electron donor (P+) by surface states of the TiO2 and (3) transient cathodic and anodic current spikes due to oxidation/reduction of TMPD/TMPD+ at the conductive glass (FTO) substrate. This model explains the origin of the photocurrent spikes that appear in this system after turning illumination on or off, the reason for the appearance of net positive or negative stable photocurrents depending on experimental conditions, and the overall efficiency of the constructed cell. The model may be a used as a guide for improvement of the photocurrent efficiency of the presented system as well as, after appropriate adjustments, other biohybrid photoelectrodes.Electronic supplementary materialThe online version of this article (10.1007/s11120-018-0550-8) contains supplementary material, which is available to authorized users.

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“…This NIR band of the RC is identified as the low energy exciton component of the Q y transition of the BChls of the P dimer. [35][36][37] Upon dehydration of RC incorporated into polyvinyl alcohol (PVA) films, 23 or embedded into glassy trehalose matrices, 21 the band maximum shifts from 866 nm to 850 nm. Such an effect has been observed as a result of a number of different perturbations of the P environment, including e.g.…”

Section: Introductionmentioning

confidence: 99%

Dehydration affects the electronic structure of the primary electron donor in bacterial photosynthetic reaction centers: evidence from visible-NIR and light-induced difference FTIR spectroscopy

Malferrari

Turina

Francia

et al. 2015

Photochem Photobiol Sci

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The photosynthetic reaction center (RC) is a membrane pigment-protein complex that catalyzes the initial charge separation reactions of photosynthesis. Following photoexcitation, the RC undergoes conformational relaxations which stabilize the charge-separated state. Dehydration of the complex inhibits its conformational dynamics, providing a useful tool to gain insights into the relaxational processes. We analyzed the effects of dehydration on the electronic structure of the primary electron donor P, as probed by visible-NIR and light-induced FTIR difference spectroscopy, in RC films equilibrated at different relative humidities r. Previous FTIR and ENDOR spectroscopic studies revealed that P, an excitonically coupled dimer of bacteriochlorophylls, can be switched between two conformations, P866 and P850, which differ in the extent of delocalization of the unpaired electron between the two bacteriochlorophyll moieties (PL and PM) of the photo-oxidized radical P(+). We found that dehydration (at r = 11%) shifts the optical Qy band of P from 866 to 850-845 nm, a large part of the effect occurring already at r = 76%. Such a dehydration weakens light-induced difference FTIR marker bands, which probe the delocalization of charge distribution within the P(+) dimer (the electronic band of P(+) at 2700 cm(-1), and the associated phase-phonon vibrational modes at around 1300, 1480, and 1550 cm(-1)). From the analysis of the P(+) keto C[double bond, length as m-dash]O bands at 1703 and 1713-15 cm(-1), we inferred that dehydration induces a stronger localization of the unpaired electron on PL(+). The observed charge redistribution is discussed in relation to the dielectric relaxation of the photoexcited RC on a long (10(2) s) time scale.

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Analysis of absorption spectra of purple bacterial reaction centers in the near infrared region by higher order derivative spectroscopy

Cited by 12 publications

References 40 publications

Mixed Upper Exciton State of the Special Pair in Bacterial Reaction Centers

Mixed Upper Exciton State of the Special Pair in Bacterial Reaction Centers

Modelling of the cathodic and anodic photocurrents from Rhodobacter sphaeroides reaction centres immobilized on titanium dioxide

Dehydration affects the electronic structure of the primary electron donor in bacterial photosynthetic reaction centers: evidence from visible-NIR and light-induced difference FTIR spectroscopy

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