Light-Induced Conformational Changes in Photosynthetic Reaction Centers: Dielectric Relaxation in the Vicinity of the Dimer

Deshmukh, Sasmit S.; Williams, Joann; Allen, James P.; Kálmán, László

doi:10.1021/bi101496c

Cited by 30 publications

(55 citation statements)

References 44 publications

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“…The probability has normalized to the maximum change in the absorption of the RC suspension at a wavelength of 870nm with an exciting light intensity of 7.2mW/cm 2 . For the analysis of electron-conformational processes in RC two models of electron transfer were used: a two-level model [6,7] and a model with four sub states [12]. According to the two-level model, the RCs are in the ground (1) state when the electron localized on the donor P. When the light quantum is absorbed, the electron moves to the Q B acceptor, and the RC goes to the excited state.…”

Section: Methodsmentioning

confidence: 99%

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Analysis are of the hidden properties of the macromolecular system as an example of the reaction centers of bacteria Rhodobacter sphaeroides

Barabash¹,

Serdenko²,

Knox³

et al. 2019

Open J Anal Bioanal Chem

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Relevant: Is the study of the response of biological macromolecules to external stimuli. Often the reaction of macromolecules has an effect of structural self-regulation. In this case, their reaction is not only external infl uence, but also the spatial-temporal motions of the macromolecule. In this situation deserves the attention of electronic-conformational interactions of macromolecules. As objects are isolated Reaction Centers (RC) of bacteria Rhodobacter sphaeroides, the structure of which is well studied. During prolonged illumination, the RC occurs intramolecular electron transfer of RC, the kinetics of which has expressed as a sum of three different exponential functions with negative values decrements. In this case, can considered two models of electron transfer with variable or constant with time of the kinetic parameters. Problem: Arises of analyzing the kinetics of electron transfer, which infl uenced by the latent parameters of the RC protein structure, which are diffi cult to determine in the experiment. Aim: Of the work is to determine the features of intramolecular electron transfer between the conformational states of RC, which are associated with a change in the structure of the macromolecule. Result: It was determined that the position of the maxima of the wavelet transform spectrum of the logarithmic derivative of the electron transfer kinetics corresponded to the minimax values of the time dependence of the probability density of the presence of an electron in various redox-conformational states of the RC (population of redox states). Minimax values of the population of RC states corresponded to: 1-6s, 30-60s, 100-140s for various parameters of RC photoexcitation. Conclusion: That the existence of minimax values of the probability density is the electron in the conformational states of the RC can related to the effects of structural self-regulation of the electron transfer process.

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Section: Methodsmentioning

confidence: 99%

“…At the same time, the mathematical form of the exponential functions has no clear features. Their parameters are interrelated and depend on the parameters of the photo excitation RC [5][6][7][8]. This makes diffi cult to physically interpret the exponential components of the electron transfer kinetics.…”

Section: Introductionmentioning

confidence: 99%

Analysis are of the hidden properties of the macromolecular system as an example of the reaction centers of bacteria Rhodobacter sphaeroides

Barabash¹,

Serdenko²,

Knox³

et al. 2019

Open J Anal Bioanal Chem

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show abstract

“…The energy of protein reorganization is changing, which leads to a change in the kinetics of electron transfer. The interrelation of electron transfer processes and changes in the protein structure of RC [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] appears. The kinetics of electron transfer acquires a multi exponential character.…”

Section: Introductionmentioning

confidence: 99%

Use of a system of differential equations to analyze the functioning of a catalytic bio macromolecule under non equilibrium conditions

Barabash

Serdenko

Knox

et al. 2019

Heliyon

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The aim of the work is to analyze the response of a biomolecule to an external influence based on the study of its hidden states by identifying differential equations with constant coefficients. The relevance of the work lies in the fact that often the main reaction of an object to an external action can be represented as a sum of various exponential functions with a common starting point and a material balance equation. In this case, the response of an object to an external action corresponds to a system of differential equations with constant coefficients. This character of the main reaction may be due to the influence of the hidden properties of the object, which play the role of regulatory parameters. The problem is that the hidden factors and the system of differential equations are not identified . As an object, isolated reaction centers (RC) of the bacteria Rhodobacter sphaeroides , which possess the above properties, has used. Their structure is well studied. As result of studying of photo excitation processes of the reaction center has shown that electron transfer kinetics (the main reaction) can be approximated by three normalized exponential functions. Program was developed to identify for four differential equations of electron transfer and the balance equation, the behavior of hidden states of the reaction center. It was concluded that time the dependence the probability density of finding an electron in different conformational states of the reaction center characterizes the space-time changes in the structure of the reaction center.

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“…Obviously, the development of long-life states with charges divided between the P dimer and quinone acceptors is related to the generalization of structural and dynamic changes in the RC. It is not possible to localize definitely the changes in RC structure, which result in the progressive slowdown of reverse reduction of P in darkness after its oxidation caused by a prolonged exposure to constant light [16,17]. Further detailed kinetic analysis of the non-monoexponentiality of the kinetics of interaction of photoactive bacteriophyll with quinone acceptor under conditions of prolonged activation of RC samples by light of different intensities can provide additional information on the structural and dynamic changes in the RC, which are related to electron transport between the P dimer and quinone acceptors.…”

Section: Introductionmentioning

confidence: 99%

The kinetic model for slow photoinduced electron transport in the reaction centers of purple bacteria

et al. 2016

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The present work is related to the investigation of slow kinetics of electron transport in the reaction centers (RCs) of Rhodobacter sphaeroides. Experimental data on the absorption kinetics of aqueous solutions of reaction centers at different modes of photoexcitation are given. It is shown that the kinetics of oxidation and reduction of RCs are well described by the sum of three exponential functions. This allows to suggest a two-level kinetic model for electron transport in the RC as a system of four electron-conformational states which correspond to three balance differential equations combined with state equation. The solution of inverse problem made it possible to obtain the rate constant values in kinetic equations for different times and intensities of exciting light. Analysis of rate constant values in different modes of RC excitation allowed to suggest that two mechanisms of structural changes are involved in RC photo-oxidation. One mechanism leads to the increment of the rate of electron return, another one-to its drop. Structural changes were found out to occur in the RCs under incident light. After light was turned off, the reduction of RCs was determined by the second mechanism.

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Light-Induced Conformational Changes in Photosynthetic Reaction Centers: Dielectric Relaxation in the Vicinity of the Dimer

Cited by 30 publications

References 44 publications

Analysis are of the hidden properties of the macromolecular system as an example of the reaction centers of bacteria Rhodobacter sphaeroides

Analysis are of the hidden properties of the macromolecular system as an example of the reaction centers of bacteria Rhodobacter sphaeroides

Use of a system of differential equations to analyze the functioning of a catalytic bio macromolecule under non equilibrium conditions

The kinetic model for slow photoinduced electron transport in the reaction centers of purple bacteria

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