Electron Transfer in Proteins

Winkler, Jay R.

doi:10.1146/annurev.bi.65.070196.002541

Cited by 1,081 publications

(943 citation statements)

References 5 publications

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“…112−115 There are multiple ways to calculate the coupling matrix elements H DA . 4,47,116,117 A fast and efficient way to obtain them is from the donor and acceptor HOMO wave functions of the neutral systems in the fragment orbital approach (FMO) 55,118 …”

Section: ■ Models and Methodsmentioning

confidence: 99%

Charge Transfer in Model Peptides: Obtaining Marcus Parameters from Molecular Simulation

et al. 2012

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Charge transfer within and between biomolecules remains a highly active field of biophysics. Due to the complexities of real systems, model compounds are a useful alternative to study the mechanistic fundamentals of charge transfer. In recent years, such model experiments have been underpinned by molecular simulation methods as well. In this work, we study electron hole transfer in helical model peptides by means of molecular dynamics simulations. A theoretical framework to extract Marcus parameters of charge transfer from simulations is presented. We find that the peptides form stable helical structures with sequence dependent small deviations from ideal PPII helices. We identify direct exposure of charged side chains to solvent as a cause of high reorganization energies, significantly larger than typical for electron transfer in proteins. This, together with small direct couplings, makes long-range superexchange electron transport in this system very slow. In good agreement with experiment, direct transfer between the terminal amino acid side chains can be dicounted in favor of a two-step hopping process if appropriate bridging groups exist. ■ INTRODUCTIONCharge transfer is a fundamental phenomenon in physical chemistry, enjoying strong and consistent scientific interest for more than fifty years. 1 Understanding charge transfer in complex and flexible biomolecules is crucial for a huge variety of processes, from cellular respiration and photosynthesis to DNA damage and repair. 2−4 Describing it accurately has turned out to be particularly challenging, both to experimentalists and theoreticians. Biochemical charge transfer involves the directed movement of electrons over large distances (multiple nanometers) through macromolecules, typically proteins or large heterogeneous multiprotein assemblies. These processes involve dynamical changes that occur on a time scale spanning multiple orders of magnitude, from subpicosecond changes in electronic structure to microsecond or even slower conformational changes. Only recently has the complicated interplay between atomic structural fluctuations and electron dynamics become a focus for charge transfer studies in biochemical systems, 5−9 building onto earlier work on model systems. 10−15 This fact, combined with the large system dimensions and difficult experimental conditions, explains why many open questions on electron transfer (ET) in biomolecules remain. Therefore, simpler model systems to study some aspects of ET have gained popularity, and theoretical models based on computer simulations have become important tools to help interpret experiments and gain a better understanding of the structure and function of the involved molecules. 16−22 An important model system in the study of charge transfer processes has always been peptide systems. Extensive experimental work was done by Isied et al., who have studied ET over distances of 8−32 Å via spectroscopical techniques and determined the properties of polyproline II helices as ET bridges. 27−34 This wo...

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Section: ■ Models and Methodsmentioning

confidence: 99%

Charge Transfer in Model Peptides: Obtaining Marcus Parameters from Molecular Simulation

et al. 2012

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“…Intra-peptide and -protein transfer of radicals has been demonstrated directly (reviewed in [6,140]). Indirect evidence also supports the occurrence of such reactions ; thus aromatic residues are normally damaged more extensively than aliphatic residues (although all are usually damaged to a significant degree), despite the fact that many of these residues are internal to a protein structure and hence not readily accessible to radicals in solution.…”

Section: Protein Oxidation In Solution In Membranes and In Lipoproteinsmentioning

confidence: 99%

Biochemistry and pathology of radical-mediated protein oxidation

Dean

Stocker

et al. 1997

Biochemical Journal

1,551

982

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Radical-mediated damage to proteins may be initiated by electron leakage, metal-ion-dependent reactions and autoxidation of lipids and sugars. The consequent protein oxidation is O2-dependent, and involves several propagating radicals, notably alkoxyl radicals. Its products include several categories of reactive species, and a range of stable products whose chemistry is currently being elucidated. Among the reactive products, protein hydroperoxides can generate further radical fluxes on reaction with transition-metal ions; protein-bound reductants (notably dopa) can reduce transition-metal ions and thereby facilitate their reaction with hydroperoxides; and aldehydes may participate in Schiff-base formation and other reactions. Cells can detoxify some of the reactive species, e.g. by reducing protein hydroperoxides to unreactive hydroxides. Oxidized proteins are often functionally inactive and their unfolding is associated with enhanced susceptibility to proteinases. Thus cells can generally remove oxidized proteins by proteolysis. However, certain oxidized proteins are poorly handled by cells, and together with possible alterations in the rate of production of oxidized proteins, this may contribute to the observed accumulation and damaging actions of oxidized proteins during aging and in pathologies such as diabetes, atherosclerosis and neurodegenerative diseases. Protein oxidation may also sometimes play controlling roles in cellular remodelling and cell growth. Proteins are also key targets in defensive cytolysis and in inflammatory self-damage. The possibility of selective protection against protein oxidation (antioxidation) is raised.

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“…[1][2][3][4][5] Much research in this area has been concerned with the kinetics of long-range electron tunneling. [6][7][8][9][10][11][12][13][14][15][16] Electron transport and related phenomena have also been a focus of substantial electrochemical investigations owing to the significance of these processes in electrocatalysis, in photoelectrochemical, electrochromic, and molecular electronic devices, and in electrochemical sensors. [17][18][19][20] Efficient electron transport over micrometer distances in multimolecular, microstructural media encountered in these systems is of crucial importance to their efficiency.…”

Section: Introductionmentioning

confidence: 99%

Structure and Lateral Electron Hopping in Osmium-tris-4,7-diphenylphenanthroline Perchlorate Monolayers at the Air/Water Interface

et al. 1999

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Osmium tris-diphenylphenanthroline perchlorate (Os(DPP) 3 ) can be spread at the air/water interface where it forms solid monolayer films. Brewster angle microscopy revealed that these films consist of irregular ca. 100 to 1000 µm diameter 2D aggregates which coalesce upon compression to form continuous films. Grazing incidence X-ray diffraction data showed that the structure of the aggregates is independent of the degree of monolayer compression and features a 2D lattice of hexagonally close-packed Os(DPP) 3 centers with Os-Os distances of 12.57 Å. The latter is 4 to 24% shorter than the Ru-Ru distances found in the 3D monoclinic crystal of an isostructural Ru (DPP) 3 . Two dimensional electrochemical measurements carried out with line microelectrodes at the air/water interface were used to study kinetics of the lateral electron transport in these Langmuir monolayers. Electron transport involves electron hopping on the 2D lattice of the osmium sites where the individual electron transfer steps between Os II (DPP) 3 and Os III (DPP) 3 take place with the rate constant k 1 ) 4.7 × 10 8 s -1 . Percolation theory was used to account for the observed increase of the electron hopping rates during monolayer compression on the water surface resulting in an increase of the extent of connectivity and thus electroactivity of the initially formed 2D Os(DPP) 3 aggregates. Percolation theory also accounts well for the dependence of the electron hopping rates on the composition of fully compressed Os-(DPP) 3 /Ru(DPP) 3 monolayers in which the ruthenium species were used to homogeneously dilute the Os-(DPP) 3 sites. In contrast, in Os(DPP) 3 /octadecanol monolayers, macroscopic self-segregation of the two components was inferred from a larger positive shift of the apparent percolation threshold in the lateral electron hopping.

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Electron Transfer in Proteins

Cited by 1,081 publications

References 5 publications

Charge Transfer in Model Peptides: Obtaining Marcus Parameters from Molecular Simulation

Charge Transfer in Model Peptides: Obtaining Marcus Parameters from Molecular Simulation

Biochemistry and pathology of radical-mediated protein oxidation

Structure and Lateral Electron Hopping in Osmium-tris-4,7-diphenylphenanthroline Perchlorate Monolayers at the Air/Water Interface

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