Direct Electrochemistry of Cofactor Redox Sites in a Bacterial Photosynthetic Reaction Center Protein

Kong, Jilie; Lu, Zhongqing; Lvov, Yuri; Desamero, Ruel Z. B.; Frank, and Harry A.; Rusling, James F.

doi:10.1021/ja981521d

Cited by 66 publications

(38 citation statements)

References 18 publications

(23 reference statements)

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“…258 This occurred for a bacterial reaction center, 287 photosystems I 288 and II, 289 bovine milk xanthine oxidase, 290 Rhodobacter capsulatus xanthine dehydrogenase 183 and DMSO reductase, [291][292][293] For adsorbed enzymes, a preliminary diagnosis of health can come from noncatalytic electrochemical studies themselves, since the conformity of the peaks to ideal predictions (section 2.1) reports on the homogeneity of reduction potentials, and the values of the measured reduction potentials can be compared to those measured under potentiometric, equilibrium titrations. Ideally, both values should agree within a few millivolts, noting that the accuracy of redox titrations is rarely better than (10 mV.…”

Section: Observing Reasonable Noncatalytic Signalsmentioning

confidence: 99%

Direct Electrochemistry of Redox Enzymes as a Tool for Mechanistic Studies

2008

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Section: Observing Reasonable Noncatalytic Signalsmentioning

confidence: 99%

Direct Electrochemistry of Redox Enzymes as a Tool for Mechanistic Studies

2008

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“…Films of phosphatidylcholine or dimyristoylphosphatidylcholine have allowed the immobilization of photosynthetic reaction centers (Kong et al , 1998 ;Munge et al , 2003 ;Alcantara et al , 2006 ).…”

Section: Mixed Protein/lipid Filmsmentioning

confidence: 99%

Recent advances in the electrochemistry and spectroelectrochemistry of membrane proteins

Melin

Hellwig

2013

Biological Chemistry

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Abstract:Integral membrane proteins are encountered in fundamental natural processes, such as photosynthesis and respiration. The relation between the structure of the proteins and their function and dynamics are still not clear in most cases. Once fully understood, these processes could ultimately help researchers to develop alternative methods for producing energy, either from light or biomass. They could also lead to more efficient antibiotics, which would selectively inhibit a specific membrane protein of pathogenic bacteria. Since the chemical reactions involved in both photosynthesis and respiration are redox reactions, electrochemical methods can play a considerable role in uncovering their mechanisms. The electrochemical characterization of membrane proteins is, however, quite challenging. An overview on the techniques used for the characterization of membrane proteins, including classical approaches such as voltammetry and spectroelectrochemistry, and recent developments, such as their combination with surface-enhanced techniques is given.

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“…From these quantities, only the driving force, , is directly accessible to measurement, e.g., by delayed fluorescence (5), redox titration (6), or voltammetry (7). The other two parameters can be determined only indirectly from kinetic data and are difficult to disentangle in practice.…”

mentioning

confidence: 99%

Structural, dynamic, and energetic aspects of long-range electron transfer in photosynthetic reaction centers

Kriegl

Nienhaus

2003

Proc. Natl. Acad. Sci. U.S.A.

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Intramolecular electron transfer within proteins plays an essential role in biological energy transduction. Electron donor and acceptor cofactors are bound in the protein matrix at specific locations, and protein-cofactor interactions as well as protein conformational changes can markedly influence the electron transfer rates. To assess these effects, we have investigated charge recombination from the primary quinone acceptor to the special pair bacteriochlorophyll dimer in wild-type reaction centers of Rhodobacter sphaeroides and four mutants with widely modified free energy gaps. After light-induced charge separation, the recombination kinetics were measured in the light-and dark-adapted forms of the protein from 10 to 300 K. The data were analyzed by using the spin-boson model, which allowed us to self-consistently determine the electronic coupling energy, the distribution of energy gaps, the spectral density of phonons, and the reorganization energy. The analysis revealed slow changes of the energy gap after charge separation. Interesting correlations of the control parameters governing electron transfer were found and related to structural and dynamic properties of the protein.T he bioenergetic pathways of living systems involve a multitude of electron transfer (ET) reactions. Within large protein-cofactor complexes, electrons tunnel between donor and acceptor sites over substantial distances (5-30 Å). In the weak coupling regime, the ET rate coefficient is obtained from perturbation theory as (1-4)where ប and V denote Planck's constant divided by 2 and the electronic coupling matrix element, respectively. The thermally averaged Franck-Condon factor, FC, represents the probability of forming a resonant complex between donor and acceptor. This quantity can be calculated in various ways, based on classical, semiclassical, or quantum-mechanical theories (4). In the celebrated classical Marcus theory (1),with Boltzmann's constant, k B , and absolute temperature, T. The free energy difference between the reactant and product states, , the nuclear reorganization energy, , and the electronic coupling, V, are the three system parameters that govern the ET rate. From these quantities, only the driving force, , is directly accessible to measurement, e.g., by delayed fluorescence (5), redox titration (6), or voltammetry (7). The other two parameters can be determined only indirectly from kinetic data and are difficult to disentangle in practice. The intrinsic flexibility of proteins adds an interesting dynamic aspect to the ET reaction. Proteins fluctuate thermally among many different conformations and respond to charge rearrangements with structural relaxations on time scales ranging from (below) picoseconds to (at least) seconds. These motions can strongly affect the ET parameters and hence the ET rates (8-10). For studying biological ET, the photosynthetic reaction center (RC) of the purple bacterium Rhodobacter sphaeroides is a superb model system. This membrane-spanning, 120-kDa, protein-pigment complex consists...

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Direct Electrochemistry of Cofactor Redox Sites in a Bacterial Photosynthetic Reaction Center Protein

Cited by 66 publications

References 18 publications

Direct Electrochemistry of Redox Enzymes as a Tool for Mechanistic Studies

Direct Electrochemistry of Redox Enzymes as a Tool for Mechanistic Studies

Recent advances in the electrochemistry and spectroelectrochemistry of membrane proteins

Structural, dynamic, and energetic aspects of long-range electron transfer in photosynthetic reaction centers

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