Long range electron transfer in helical polyproline II oligopeptides

Ogawa, Michael Y.; Moreira, Ícaro de Sousa; Wishart, James F.; Isied, Stephan S.

doi:10.1016/0301-0104(93)80263-9

Cited by 57 publications

(62 citation statements)

References 38 publications

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“…This pathway is characterized by a low value of the descriptor of the exponential distance dependence of the electron transfer rate, β ΤΒ = 2.5 ± 0.1 nm -1 , suggesting that helical segments in proteins can function as efficient channels of long-distance electron transfer. Long-range electron transfer (LRET) between various oligoproline-bridged redox pairs has been studied over the past 10 years in several laboratories (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18) with the aim of elucidating the parameters of LRET across a single peptide pathway. The choice of oligoprolines for such a study was dictated by the known ability of short H-(Pro)n-OH peptides to attain, in aqueous solution, a stable helical conformation similar to that of the 3X left-handed helix of alltrans poly-L-proline II (19)(20)(21)(22).…”

Section: Risø National Laboratory Dk-4000 Roskilde Denmarkmentioning

confidence: 99%

Long-Range Electron Transfer Between Proline-Bridged Aromatic Amino Acids

Bobrowski

Poznański

Holcman

et al. 1998

Photochemistry and Radiation Chemistry

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Interpretation of the kinetic pulse radiolysis data for intramolecular Trp --> Tyr radical transformation in aqueous solutions of linear H-Trp-(Pro)n-Tyr-OH, n = 0-5, is presented in terms of the Marcus electron transfer theory, taking into account conformational dynamics of the molecules. For this purpose, for each peptide, representative sets of low-energy conformers were selected with the help of experimental methods ( 1 H and 13 C NMR, and circular dichroism) and modeling meth ods (molecular mechanics and dynamics ); and relative electron transfer rates averaged over all the conformers were calculated for two assumed competitive electron transfer pathways: through space (TS) and through the peptide backbone (TB). The TS rates were obtained by taking into account the overlap integrals of aromatic ring orbitals calu lated quantum mechanically. By fitting the calculated rates to the experi mental data for the rate constants for electron transfer, ket, with an exponential function appropriate for the two-pathway model, we have demonstrated that in linear short-bridged peptides (n = 0-2), electron transfer predominantly takes the TS pathway, which consists of van der Waals contacts between the aromatic rings, whereas in longer peptides (n = 3-5), it occurs exclusively by the TB pathway, which is made of a -(Pro)n-bridge in a helical conformation similar to that of all-trans poly-L-proline II. This pathway is characterized by a low value of the descriptor of the exponential distance dependence of the electron transfer rate, β ΤΒ = 2.5 ± 0.1 nm -1 , suggesting that helical segments in proteins can function as efficient channels of long-distance electron transfer.

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Section: Risø National Laboratory Dk-4000 Roskilde Denmarkmentioning

confidence: 99%

Long-Range Electron Transfer Between Proline-Bridged Aromatic Amino Acids

Bobrowski

Poznański

Holcman

et al. 1998

Photochemistry and Radiation Chemistry

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“…[1][2][3][4] Among them, the ET reactions between local donor (D) and acceptor (A) groups linked by organic spacer molecules (bridge, B) have been thoroughly investigated experimentally. [5][6][7][8][9][10] Such ET reactions occur in the non-adiabatic limit and the rate of reaction is given by the following formula: [1][2][3][4]…”

Section: Introductionmentioning

confidence: 99%

Pathway analysis of super-exchange electronic couplings in electron transfer reactions using a multi-configuration self-consistent field method

Nishioka

Ando

2011

Phys. Chem. Chem. Phys.

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We present a novel pathway analysis of super-exchange electronic couplings in electron transfer reactions using localized molecular orbitals from multi-configuration self-consistent field (MCSCF) calculations. In our analysis, the electronic coupling and the tunneling pathways can be calculated in terms of the configuration interaction (CI) Hamiltonian matrix obtained from the localized MCSCF wave function. Making use of the occupation restricted multiple active spaces (ORMAS) method can effectively produce the donor, acceptor, and intermediate configuration state functions (CSFs) and CIs among these CSFs. In order to express the electronic coupling as a sum of individual tunneling pathways contributions, we employed two perturbative methods: Löwdin projection-iteration method and higher-order super-exchange method. We applied them to anion couplings of butane-1,4-diyl and pentane-1,5-diyl. The results were (1) the electronic couplings calculated from the two perturbative methods were in reasonable agreement with those from a non-perturbative method (one-half value of the energy difference between the ground and first excited states), (2) the main tunneling pathways consisted of a small number of lower-order super-exchange pathways where bonding, anti-bonding, or extra-valence-shell orbitals were used once or twice, and (3) the interference among a huge number of higher-order super-exchange pathways significantly contributed to the overall electronic coupling, whereas each of them contributed only fractionally. Our method can adequately take into account both effects of non-dynamical electron correlation and orbital relaxation. Comparing with the analyses based on the Koopmans' theorem (ignoring both effects) and the ORMAS-CIs from frozen localized reference orbitals (ignoring the effect of orbital relaxation), we discuss these effects.

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] In biological molecules such as cytochromes, hemoglobins, DNA, and docked proteins longrange electron transfer has been investigated over time scales running down to the femtosecond regime, and it is generally found that, in the nonadiabatic regime, the rate of electron transfer decays roughly exponentially with distance between donor and acceptor sites. 7,11 Synthetic molecules have been prepared by a number of research groups, to investigate specifically the rate of nonadiabatic intramolecular electron transfer as the relative geometries and energetics of the donor and acceptor moieties vary and, particularly, as the distance between donor and acceptor, linked together by rigid bridges, is varied. 5 For example, Chart 1 shows several molecules prepared in our group for the study of such electron transfer phenomena.…”

Section: Introductionmentioning

confidence: 99%

Electron Transfer Rates in Bridged Molecular Systems: A Phenomenological Approach to Relaxation

Davis¹,

Wasielewski

Ratner³

et al. 1997

J. Phys. Chem. A

190

170

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A model for bridge-assisted, long-range electron transfer in a molecule interacting with a dissipative external bath is presented. The effects of the system-bath interaction are included phenomenologically in the evolution of the system density matrix as energy dephasings on the bridge sites. When the bridge dephasings are small, the steady state ET rate in this model is found to be the sum of two competing terms; the first is a McConnell-type rate arising from direct tunneling from donor to acceptor, and the second is a dephasingdependent, length-independent scattering channel through the bridge sites. In the limit of large dephasings, an incoherent channel dominates the dynamics and leads to ET rates that can become only weakly dependent (k ET ∝ 1/N) on the number of bridge sites in the system, for multisite bridges.

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Long range electron transfer in helical polyproline II oligopeptides

Cited by 57 publications

References 38 publications

Long-Range Electron Transfer Between Proline-Bridged Aromatic Amino Acids

Long-Range Electron Transfer Between Proline-Bridged Aromatic Amino Acids

Pathway analysis of super-exchange electronic couplings in electron transfer reactions using a multi-configuration self-consistent field method

Electron Transfer Rates in Bridged Molecular Systems: A Phenomenological Approach to Relaxation

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