Estimation of the rate of photochemical charge separation in <i>Rhodopseudomonas sphaeroides</i> reaction centers by fluorescence and absorption picosecond spectroscopy

Paschenko, V.Z.; Korvatovskii, B. N.; Kononenko, A.A.; Chamorovsky, Sergey K.; Rubin, A. B.

doi:10.1016/0014-5793(85)80017-x

Cited by 27 publications

(5 citation statements)

References 13 publications

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“…The M-branch pigments display electrochromic shifts in response to the charge separation process in the L-branch, however (Kirmaier et al 19856). Comparison of fluorescence lifetimes and appearance kinetics of H~ over the temperature range from 293 to 77 K revealed the same kinetics in the two measurements thus also arguing against a Bĩ ntermediate (Paschenko et al 1985). Subsequent femtosecond absorption experiments were carried out by several groups and applied to various reaction centre types.…”

Section: Charge Separation In Bacterial Photosynthetic Reaction Centresmentioning

confidence: 99%

Applications of ultrafast laser spectroscopy for the study of biological systems

Holzwarth

1989

Quart. Rev. Biophys.

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The discovery of mode-locked laser operation now nearly two decades ago has started a development which enables researchers to probe the dynamics of ultrafast physical and chemical processes at the molecular level on shorter and shorter time scales. Naturally the first applications were in the fields of photophysics and photochemistry where it was then possible for the first time to probe electronic and vibrational relaxation processes on a sub-nanosecond timescale. The development went from lasers producing pulses of many picoseconds to the shortest pulses which are at present just a few femtoseconds long. Soon after their discovery ultrashort pulses were applied also to biological systems which has revealed a wealth of information contributing to our understanding of a broadrange of biological processes on the molecular level.It is the aim of this review to discuss the recent advances and point out some future trends in the study of ultrafast processes in biological systems using laser techniques. The emphasis will be mainly on new results obtained during the last 5 or 6 years. The term ultrafast means that I shall restrict myself to sub-nanosecond processes with a few exceptions.

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Section: Charge Separation In Bacterial Photosynthetic Reaction Centresmentioning

confidence: 99%

Applications of ultrafast laser spectroscopy for the study of biological systems

Holzwarth

1989

Quart. Rev. Biophys.

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“…Excitation at wavelengths such as 600 or 532 nm add the complication that the absorption changes and kinetics associated with excited states of the other pigments, and energy transfer to P, might obfuscate the initial electron transfer step (these topics are interesting in their own right however). Until recently, experiments employing 7 to 30 ps flashes have provided most of our information about the kinetics of the formation of P+ I- [2,14,41,49,60,61,69,70,72,74,97,98,116,125,128,135,138,[140][141][142].…”

Section: H Initial Charge Separationmentioning

confidence: 99%

Primary photochemistry of reaction centers from the photosynthetic purple bacteria

1987

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Photosynthetic organisms transform the energy of sunlight into chemical potential in a specialized membrane-bound pigment-protein complex called the reaction center. Following light activation, the reaction center produces a charge-separated state consisting of an oxidized electron donor molecule and a reduced electron acceptor molecule. This primary photochemical process, which occurs via a series of rapid electron transfer steps, is complete within a nanosecond of photon absorption. Recent structural data on reaction centers of photosynthetic bacteria, combined with results from a large variety of photochemical measurements have expanded our understanding of how efficient charge separation occurs in the reaction center, and have changed many of the outstanding questions.

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“…Absorption changes, resulting from electron transfer within the PIQA system, were recorded as in [3,4] on a computer-based picosecond spectrometer. A pulse selectivity technique was used for excitation (A,, = 532 nm) and probe (A = 870 and 750 nm) pulses to maintain the pulse energy and duration within the specified limits.…”

Section: Methodsmentioning

confidence: 99%

“…The thermal effects in the primary photosynthetic reactions are not large [3,4,. At physiological and low temperatures (down to liquid helium temperature) electron transfer from P to QA takes about 100 ps.…”

Section: Introductionmentioning

confidence: 99%

“…These fast reactions (scheme 1) hv PIQA --+ P*IQA + P+I-QA + P+IQA (1) proceed with a high quantum and energetic efficiency in the so-called reaction center (RC), a protein complex to which pigments and electron transport cofactors are specifically linked. The thermal effects in the primary photosynthetic reactions are not large [3,4,. At physiological and low temperatures (down to liquid helium temperature) electron transfer from P to QA takes about 100 ps.…”

Section: Introductionmentioning

confidence: 99%

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Modification of protein hydrogen bonds influences the efficiency of picosecond electron transfer in bacterial photosynthetic reaction centers

et al. 1987

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Picosecond absorption spectroscopy was used to monitor laser-induced oxidation-reductions of reaction center (RC) bacteriochlorophyll (P) and bacteriopheophytin (I) in Rhodopseudomonas sphaeroides RC preparations on exposure to different chemicals. The DrO isotope substitution of H20 or partial substitution of water by organic solvents (ethylene glycol, glycerol, propylene glycol, dimethyl sulfoxide) causes the appearance of a fast, nanosecond component of P+ reduction, the result of an increased probability of recombination of the primary ion-radical products P+II + PI. The effect is accompanied by a noticeable slowing down of electron transfer from photoreduced bacteriopheophytin to the primary quinone acceptor QA. The effect of the organic solvents, kncwn as cryoprotectors, is correlated with their degree of hydrophobicity, i.e. the ability to penetrate the RC protein and interact with bound water and protein hydrogen bonds. The conclusion drawn from the data is that the dielectric relaxation processes through which the intermediate energy levels of the carriers in the PIQA system are lowered to levels necessary for the stabilization of the photochemically separated charges proceed with the involvement of protons of the nearest water-protein surrounding of the RC pigments and electron transport cofactors.

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Estimation of the rate of photochemical charge separation in Rhodopseudomonas sphaeroides reaction centers by fluorescence and absorption picosecond spectroscopy

Cited by 27 publications

References 13 publications

Applications of ultrafast laser spectroscopy for the study of biological systems

Applications of ultrafast laser spectroscopy for the study of biological systems

Primary photochemistry of reaction centers from the photosynthetic purple bacteria

Modification of protein hydrogen bonds influences the efficiency of picosecond electron transfer in bacterial photosynthetic reaction centers

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