Electron transport networks in multicentre metalloproteins

Christensen, Hans Erik Mølager; Coutinho, Isabel; Conrad, Lars S.; Hammerstad-Pedersen, Jan M.; Iversen, Gitte; Jensen, Marianne H.; Karlsson, Jens-Jakob; Ulstrup, Jens; Xavier, António V.

doi:10.1016/1010-6030(94)87009-8

Cited by 16 publications

(10 citation statements)

References 43 publications

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“…particular, some cases such as the interaction between haems I and II and between haems I and IV show an apparent dielectric constant larger than that of the solvent. Large values for the apparent dielectric constant have been predicted from electrostatic calculations by using the structure of cytochrome c 3 , [12] and were also reported for other systems. [31] In the latter case, they were interpreted as resulting from the contribution of the overall protein dipole to the charge ± charge interaction.…”

Section: Discussionmentioning

confidence: 99%

Cooperativity between Electrons and Protons in a Monomeric Cytochrome c3: The Importance of Mechano-Chemical Coupling for Energy Transduction

et al. 2001

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To fully understand the structural bases for the mechanisms of biological energy transduction, it is essential to determine the microscopic thermodynamic parameters which describe the properties of each centre involved in the reactions, as well as its interactions with the others. These interactions between centres can then be interpreted in the light of structural features of the proteins. Redox titrations of cytochrome c(3) from Desulfovibrio desulfuricans ATCC 27774 followed by NMR and visible spectroscopy were analysed by using an equilibrium thermodynamic model. The network of homotropic and heterotropic cooperativities results in the coupled transfer of electrons and protons under physiological conditions. The microscopic characterisation allows the identification of several pairs of centres for which there are clear conformational (non-Coulombic) contributions to their coupling energies, thus establishing the existence of localised redox- and acid-base-linked structural modifications in the protein (mechano-chemical coupling). The modulation of interactions between centres observed for this cytochrome may be an important general phenomenon and is discussed in the framework of its physiological function and of the current focus of energy transduction research.

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Section: Discussionmentioning

confidence: 99%

Cooperativity between Electrons and Protons in a Monomeric Cytochrome c3: The Importance of Mechano-Chemical Coupling for Energy Transduction

et al. 2001

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“…Different strategies can be used to evaluate the signal intensity associated with each spectral component: (i) to simulate the EPR spectra, (ii) to evaluate the intensity of non‐overlapping features (e.g., the non‐overlapping features at g ∥ of Nir, Figure 8, A),41a (iii) to take EPR spectra as a function of temperature (Figure 8, B),44a or (iv) to evaluate the intensity of the more intense spectral peak of overlapped EPR signals (e.g., the peak that arises from the sum of the g ⟂ features of both T1 and T2 centers, Figure 9). 45 Analysis of the data is usually performed by assuming independent Nernst equations that are least‐squares fit to the data, though in some cases it is necessary to take cooperative effects between the redox centers into consideration 46…”

Section: Cw Epr Of Biological Macromoleculesmentioning

confidence: 99%

EPR as a Tool for Study of Isolated and Coupled Paramagnetic Centers in Coordination Compounds and Macromolecules of Biological Interest

et al. 2015

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Continuous Wave Electron Paramagnetic Resonance (CW EPR) is an essential spectroscopic tool for study of systems containing unpaired electrons. The potential capability of the technique has extended its use beyond being solely by experts, and today it is widely used by non-specialists. In this microreview we present selected examples together with basic theoretical aspects necessary for understanding of the EPR properties of isolated paramagnetic centers and assemblies of them

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“…Using the Marquardt method to fit a set of traces, with a value of 1 eV for the reorganisation energy [15] and independent parameters for the four haems (model 1), gave rates close to zero for haems 2 and 3. Therefore, these rates were fixed at zero and the resulting simulations, shown in Figure 4, have only two fitted parameters.…”

Section: Analysis Of the Kinetics Of Reduction Of A Tetrahaem Proteinmentioning

confidence: 99%

Thermodynamic Control of Electron Transfer Rates in Multicentre Redox Proteins

Catarino

Turner

2001

ChemBioChem

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In the analysis of kinetic data from multicentre redox proteins, it is essential to distinguish between the observable macroscopic rate constants and the structurally relevant microscopic properties. This distinction is complicated by the existence of interactions between centres. The problem is illustrated by the case of two interacting redox centres and generalised for the analysis of stopped-flow kinetic data for the reduction of cytochrome c(3), in which four redox centres and at least one proteolytic centre are mutually interacting. It is shown that fast intramolecular electron transfer, which is typical of many multicentre redox proteins, and, where present, fast proton exchange, ensure that only N rate constants can be measured for a protein with N redox centres. The equations that relate the observable macroscopic rate constants to the microscopic rate constants of individual centres depend on a set of parameters that can be approximated by using the Marcus theory of electron transfer together with a set of reasonable assumptions. The results are tested by fitting experimental data for the reduction of cytochrome c(3) by sodium dithionite, including its pH dependence.

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Electron transport networks in multicentre metalloproteins

Cited by 16 publications

References 43 publications

Cooperativity between Electrons and Protons in a Monomeric Cytochrome c3: The Importance of Mechano-Chemical Coupling for Energy Transduction

Cooperativity between Electrons and Protons in a Monomeric Cytochrome c3: The Importance of Mechano-Chemical Coupling for Energy Transduction

EPR as a Tool for Study of Isolated and Coupled Paramagnetic Centers in Coordination Compounds and Macromolecules of Biological Interest

Thermodynamic Control of Electron Transfer Rates in Multicentre Redox Proteins

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