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Lacombat F, Espagne A, Dozova N, Plaza P, Müller P, Emmerich HJ, Saft M, Essen LO. Ultrafast photoreduction dynamics of a new class of CPD photolyases. Photochem Photobiol Sci 2021; 20:733-746. [PMID: 33977513 DOI: 10.1007/s43630-021-00048-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 04/22/2021] [Indexed: 01/09/2023]
Abstract
NewPHL is a recently discovered subgroup of ancestral DNA photolyases. Its domain architecture displays pronounced differences from that of canonical photolyases, in particular at the level of the characteristic electron transfer chain, which is limited to merely two tryptophans, instead of the "classical" three or four. Using transient absorption spectroscopy, we show that the dynamics of photoreduction of the oxidized FAD cofactor in the NewPHL begins similarly as that in canonical photolyases, i.e., with a sub-ps primary reduction of the excited FAD cofactor by an adjacent tryptophan, followed by migration of the electron hole towards the second tryptophan in the tens of ps regime. However, the resulting tryptophanyl radical then undergoes an unprecedentedly fast deprotonation in less than 100 ps in the NewPHL. In spite of the stabilization effect of this deprotonation, almost complete charge recombination follows in two phases of ~ 950 ps and ~ 50 ns. Such a rapid recombination of the radical pair implies that the first FAD photoreduction step, i.e., conversion of the fully oxidized to the semi-quinone state, should be rather difficult in vivo. We hence suggest that the flavin chromophore likely switches only between its semi-reduced and fully reduced form in NewPHL under physiological conditions.
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Affiliation(s)
- Fabien Lacombat
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL University, CNRS, Sorbonne Université, 75005, Paris, France
| | - Agathe Espagne
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL University, CNRS, Sorbonne Université, 75005, Paris, France
| | - Nadia Dozova
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL University, CNRS, Sorbonne Université, 75005, Paris, France
| | - Pascal Plaza
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL University, CNRS, Sorbonne Université, 75005, Paris, France.
| | - Pavel Müller
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, 91198, Gif-sur-Yvette, France.
| | - Hans-Joachim Emmerich
- Department of Chemistry, Center for Synthetic Microbiology, Philipps University, 35032, Marburg, Germany
| | - Martin Saft
- Department of Chemistry, Center for Synthetic Microbiology, Philipps University, 35032, Marburg, Germany
| | - Lars-Oliver Essen
- Department of Chemistry, Center for Synthetic Microbiology, Philipps University, 35032, Marburg, Germany.
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2
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Lawrence JE, Manolopoulos DE. Confirming the role of nuclear tunneling in aqueous ferrous–ferric electron transfer. J Chem Phys 2020; 153:154114. [DOI: 10.1063/5.0022678] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- Joseph E. Lawrence
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - David E. Manolopoulos
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
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3
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Bialas C, Barnard DT, Auman DB, McBride RA, Jarocha LE, Hore PJ, Dutton PL, Stanley RJ, Moser CC. Ultrafast flavin/tryptophan radical pair kinetics in a magnetically sensitive artificial protein. Phys Chem Chem Phys 2019; 21:13453-13461. [PMID: 31187821 DOI: 10.1039/c9cp01916b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Radical pair formation and decay are implicated in a wide range of biological processes including avian magnetoreception. However, studying such biological radical pairs is complicated by both the complexity and relative fragility of natural systems. To resolve open questions about how natural flavin-amino acid radical pair systems are engineered, and to create new systems with novel properties, we developed a stable and highly adaptable de novo artificial protein system. These protein maquettes are designed with intentional simplicity and transparency to tolerate aggressive manipulations that are impractical or impossible in natural proteins. Here we characterize the ultrafast dynamics of a series of maquettes with differing electron-transfer distance between a covalently ligated flavin and a tryptophan in an environment free of other potential radical centers. We resolve the spectral signatures of the cysteine-ligated flavin singlet and triplet states and reveal the picosecond formation and recombination of singlet-born radical pairs. Magnetic field-sensitive triplet-born radical pair formation and recombination occurs at longer timescales. These results suggest that both triplet- and singlet-born radical pairs could be exploited as biological magnetic sensors.
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Affiliation(s)
- Chris Bialas
- Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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Na S, Jurkovic S, Friedrich T, Koslowski T. Charge transfer through a fragment of the respiratory complex I and its regulation: an atomistic simulation approach. Phys Chem Chem Phys 2018; 20:20023-20032. [PMID: 30022212 DOI: 10.1039/c8cp02420k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We simulate electron transfer within a fragment of the NADH:ubiquinone oxidoreductase (respiratory complex I) of the hyperthermophilic bacterium Aquifex aeolicus. We apply molecular dynamics simulations, thermodynamic integration, and a thermodynamic network least squares analysis to compute two key parameters of Marcus' theory of charge transfer, the thermodynamic driving force and the reorganization energy. Intramolecular contributions to the Gibbs free energy differences of electron and hydrogen transfer processes, ΔG, are accessed by calibrating against experimental redox titration data. This approach permits the computation of the interactions between the species NAD+, FMNH2, N1a-, and N3-, and the construction of a free energy surface for the flow of electrons within the fragment. We find NAD+ to be a strong candidate for the regulation of charge transfer.
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Affiliation(s)
- Sehee Na
- Institut für Physikalische Chemie, Universität Freiburg, Albertstraße23a, 79104 Freiburg im Breisgau, Germany.
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5
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Mattiat J, Richardson JO. Effects of tunnelling and asymmetry for system-bath models of electron transfer. J Chem Phys 2018; 148:102311. [PMID: 29544261 DOI: 10.1063/1.5001116] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We apply the newly derived nonadiabatic golden-rule instanton theory to asymmetric models describing electron-transfer in solution. The models go beyond the usual spin-boson description and have anharmonic free-energy surfaces with different values for the reactant and product reorganization energies. The instanton method gives an excellent description of the behaviour of the rate constant with respect to asymmetry for the whole range studied. We derive a general formula for an asymmetric version of the Marcus theory based on the classical limit of the instanton and find that this gives significant corrections to the standard Marcus theory. A scheme is given to compute this rate based only on equilibrium simulations. We also compare the rate constants obtained by the instanton method with its classical limit to study the effect of tunnelling and other quantum nuclear effects. These quantum effects can increase the rate constant by orders of magnitude.
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Affiliation(s)
- Johann Mattiat
- Laboratory of Physical Chemistry, ETH Zurich, 8093 Zurich, Switzerland
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6
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Holub D, Ma H, Krauß N, Lamparter T, Elstner M, Gillet N. Functional role of an unusual tyrosine residue in the electron transfer chain of a prokaryotic (6-4) photolyase. Chem Sci 2017; 9:1259-1272. [PMID: 29675172 PMCID: PMC5887102 DOI: 10.1039/c7sc03386a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 12/09/2017] [Indexed: 11/21/2022] Open
Abstract
Cryptochromes and photolyases form a flavoprotein family in which the FAD chromophore undergoes light induced changes of its redox state. During this process, termed photoreduction, electrons flow from the surface via conserved amino acid residues to FAD. The bacterial (6-4) photolyase PhrB belongs to a phylogenetically ancient group. Photoreduction of PhrB differs from the typical pattern because the amino acid of the electron cascade next to FAD is a tyrosine (Tyr391), whereas photolyases and cryptochromes of other groups have a tryptophan as direct electron donor of FAD. Mutagenesis studies have identified Trp342 and Trp390 as essential for charge transfer. Trp342 is located at the periphery of PhrB while Trp390 connects Trp342 and Tyr391. The role of Tyr391, which lies between Trp390 and FAD, is however unclear as its replacement by phenylalanine did not block photoreduction. Experiments reported here, which replace Tyr391 by Ala, show that photoreduction is blocked, underlining the relevance of Tyr/Phe at position 391 and indicating that charge transfer occurs via the triad 391-390-342. This raises the question, why PhrB positions a tyrosine at this location, having a less favourable ionisation potential than tryptophan, which occurs at this position in many proteins of the photolyase/cryptochrome family. Tunnelling matrix calculations show that tyrosine or phenylalanine can be involved in a productive bridged electron transfer between FAD and Trp390, in line with experimental findings. Since replacement of Tyr391 by Trp resulted in loss of FAD and DMRL chromophores, electron transfer cannot be studied experimentally in this mutant, but calculations on a mutant model suggest that Trp might participate in the electron transfer cascade. Charge transfer simulations reveal an unusual stabilization of the positive charge on site 391 compared to other photolyases or cryptochromes. Water molecules near Tyr391 offer a polar environment which stabilizes the positive charge on this site, thereby lowering the energetic barrier intrinsic to tyrosine. This opens a second charge transfer channel in addition to tunnelling through the tyrosine barrier, based on hopping and therefore transient oxidation of Tyr391, which enables a fast charge transfer similar to proteins utilizing a tryptophan-triad. Our results suggest that evolution of the first site of the redox chain has just been possible by tuning the protein structure and environment to manage a downhill hole transfer process from FAD to solvent.
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Affiliation(s)
- Daniel Holub
- Department for Theoretical Chemical Biology , Institute for Physical Chemistry , Karlsruhe Institute for Technology , Kaiserstr. 12 , 76131 , Karlsruhe , Germany .
| | - Hongju Ma
- Botanical Institute , Karlsruhe Institute for Technology , Fritz Haber Weg 4 , 76131 , Karlsruhe , Germany
| | - Norbert Krauß
- Botanical Institute , Karlsruhe Institute for Technology , Fritz Haber Weg 4 , 76131 , Karlsruhe , Germany
| | - Tilman Lamparter
- Botanical Institute , Karlsruhe Institute for Technology , Fritz Haber Weg 4 , 76131 , Karlsruhe , Germany
| | - Marcus Elstner
- Department for Theoretical Chemical Biology , Institute for Physical Chemistry , Karlsruhe Institute for Technology , Kaiserstr. 12 , 76131 , Karlsruhe , Germany . .,Institute of Biological Interfaces (IGB2) , Karlsruhe Institute for Technology , Kaiserstr. 12 , 76131 , Karlsruhe , Germany
| | - Natacha Gillet
- Department for Theoretical Chemical Biology , Institute for Physical Chemistry , Karlsruhe Institute for Technology , Kaiserstr. 12 , 76131 , Karlsruhe , Germany .
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7
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Na S, Bauß A, Langenmaier M, Koslowski T. Thermodynamic integration network study of electron transfer: from proteins to aggregates. Phys Chem Chem Phys 2017; 19:18938-18947. [DOI: 10.1039/c7cp03030d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We describe electron transfer through the NrfHA nitrite reductase using a thermodynamic integration scheme. Driving forces are hardly affected by dimerization, but the transport mechanism only emerges simulating the dimer.
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Affiliation(s)
- Sehee Na
- Institut für Physikalische Chemie
- Universität Freiburg
- D-79104 Freiburg im Breisgau
- Germany
| | - Anna Bauß
- Institut für Physikalische Chemie
- Universität Freiburg
- D-79104 Freiburg im Breisgau
- Germany
| | - Michael Langenmaier
- Institut für Physikalische Chemie
- Universität Freiburg
- D-79104 Freiburg im Breisgau
- Germany
| | - Thorsten Koslowski
- Institut für Physikalische Chemie
- Universität Freiburg
- D-79104 Freiburg im Breisgau
- Germany
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8
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Bauß A, Langenmaier M, Strittmatter E, Plattner DA, Koslowski T. Thermodynamic Integration Networks and Their Application to Charge Transfer Reactions within the AauDyPI Fungal Peroxidase. J Phys Chem B 2016; 120:4937-44. [DOI: 10.1021/acs.jpcb.6b03327] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Anna Bauß
- Institut
für Physikalische Chemie, Universität Freiburg, Albertstraße
23a, D-79104 Freiburg
im Breisgau, Germany
| | - Michael Langenmaier
- Institut
für Physikalische Chemie, Universität Freiburg, Albertstraße
23a, D-79104 Freiburg
im Breisgau, Germany
| | - Eric Strittmatter
- Institut
für Organische Chemie, Universität Freiburg, Albertstraße
21, D-79104 Freiburg
im Breisgau, Germany
| | - Dietmar A. Plattner
- Institut
für Organische Chemie, Universität Freiburg, Albertstraße
21, D-79104 Freiburg
im Breisgau, Germany
| | - Thorsten Koslowski
- Institut
für Physikalische Chemie, Universität Freiburg, Albertstraße
23a, D-79104 Freiburg
im Breisgau, Germany
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9
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Richardson JO, Bauer R, Thoss M. Semiclassical Green’s functions and an instanton formulation of electron-transfer rates in the nonadiabatic limit. J Chem Phys 2015; 143:134115. [DOI: 10.1063/1.4932361] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Jeremy O. Richardson
- Institut für Theoretische Physik und Interdisziplinäres Zentrum für Molekulare Materialien, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Staudtstraße 7/B2, 91058 Erlangen, Germany
| | - Rainer Bauer
- Institut für Theoretische Physik und Interdisziplinäres Zentrum für Molekulare Materialien, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Staudtstraße 7/B2, 91058 Erlangen, Germany
| | - Michael Thoss
- Institut für Theoretische Physik und Interdisziplinäres Zentrum für Molekulare Materialien, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Staudtstraße 7/B2, 91058 Erlangen, Germany
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10
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Nohr D, Rodriguez R, Weber S, Schleicher E. How can EPR spectroscopy help to unravel molecular mechanisms of flavin-dependent photoreceptors? Front Mol Biosci 2015; 2:49. [PMID: 26389123 PMCID: PMC4555020 DOI: 10.3389/fmolb.2015.00049] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 08/10/2015] [Indexed: 11/25/2022] Open
Abstract
Electron paramagnetic resonance (EPR) spectroscopy is a well-established spectroscopic method for the examination of paramagnetic molecules. Proteins can contain paramagnetic moieties in form of stable cofactors, transiently formed intermediates, or spin labels artificially introduced to cysteine sites. The focus of this review is to evaluate potential scopes of application of EPR to the emerging field of optogenetics. The main objective for EPR spectroscopy in this context is to unravel the complex mechanisms of light-active proteins, from their primary photoreaction to downstream signal transduction. An overview of recent results from the family of flavin-containing, blue-light dependent photoreceptors is given. In detail, mechanistic similarities and differences are condensed from the three classes of flavoproteins, the cryptochromes, LOV (Light-oxygen-voltage), and BLUF (blue-light using FAD) domains. Additionally, a concept that includes spin-labeled proteins and examination using modern pulsed EPR is introduced, which allows for a precise mapping of light-induced conformational changes.
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Affiliation(s)
- Daniel Nohr
- Department of Physical Chemistry, Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg Freiburg, Germany
| | - Ryan Rodriguez
- Department of Physical Chemistry, Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg Freiburg, Germany
| | - Stefan Weber
- Department of Physical Chemistry, Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg Freiburg, Germany
| | - Erik Schleicher
- Department of Physical Chemistry, Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg Freiburg, Germany
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11
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Bauß A, Koslowski T. Storage, transport, release: heme versatility in nitrite reductase electron transfer studied by molecular dynamics simulations. Phys Chem Chem Phys 2015; 17:4483-91. [DOI: 10.1039/c4cp04383a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Using molecular dynamics simulations of the thermodynamic integration type, we study the energetics and kinetics of electron transfer through the nitrite reductase enzyme of Sulfurospirillum deleyianum, Wolinella succinogenes and Campylobacter jejuni.
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Affiliation(s)
- Anna Bauß
- Institut für Physikalische Chemie
- Universität Freiburg
- D-79104 Freiburg im Breisgau
- Germany
| | - Thorsten Koslowski
- Institut für Physikalische Chemie
- Universität Freiburg
- D-79104 Freiburg im Breisgau
- Germany
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12
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Cailliez F, Müller P, Gallois M, de la Lande A. ATP binding and aspartate protonation enhance photoinduced electron transfer in plant cryptochrome. J Am Chem Soc 2014; 136:12974-86. [PMID: 25157750 DOI: 10.1021/ja506084f] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Cryptochromes are flavoproteins encountered in most vegetal and animal species. They play a role of blue-light receptors in plants and in invertebrates. The putative resting state of the FAD cofactor in these proteins is its fully oxidized form, FADox. Upon blue-light excitation, the isoalloxazine ring (ISO) may undergo an ultrafast reduction by a nearby tryptophan residue W400. This primary reduction triggers a cascade of electron and proton transfers, ultimately leading to the formation of the FADH° radical. A recent experimental study has shown that the yield of FADH° formation in Arabidopsis cryptochrome can be strongly modulated by ATP binding and by pH, affecting the protonation state of D396 (proton donor to FAD°(-)). Here we provide a detailed molecular analysis of these effects by means of combined classical molecular dynamics simulations and time-dependent density functional theory calculations. When ATP is present and D396 protonated, FAD remains in close contact with W400, thereby enhancing electron transfer (ET) from W400 to ISO*. In contrast, deprotonation of D396 and absence of ATP introduce flexibility to the photoactive site prior to FAD excitation, with the consequence of increased ISO-W400 distance and diminished tunneling rate by almost two orders of magnitude. We show that under these conditions, ET from the adenine moiety of FAD becomes a competitive relaxation pathway. Overall, our data suggest that the observed effects of ATP and pH on the FAD photoreduction find their roots in the earliest stage of the photoreduction process; i.e., ATP binding and the protonation state of D396 determine the preferred pathway of ISO* relaxation.
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Affiliation(s)
- Fabien Cailliez
- Laboratoire de Chimie Physique, UMR 8000, Université Paris-Sud and CNRS , Orsay F-91405, France
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Barbatti M. Computational reference data for the photochemistry of cyclobutane pyrimidine dimers. Chemphyschem 2014; 15:3342-54. [PMID: 25044616 DOI: 10.1002/cphc.201402302] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Indexed: 01/19/2023]
Abstract
The cis-syn cyclobutane pyrimidine dimer is one of the major classes of carcinogenic UV-induced DNA photoproducts. In this work, diverse high-level quantum-chemical methods were used to determine the spectroscopic properties of neutral (singlet and triplet) and charged (cation and anion) species of thymine dimers. Maps of potential energy, charge distribution, electron affinity, and ionization potential of the thymidine dimers were computed along the two dimerization coordinates for neutral and charged species, as well as for the singlet excited state. This set of data aims at providing consistent results computed with the same methods as for photodamage and repair. Based on these results, several different photo-, heat-, and charge-induced mechanisms of dimerization and repair are characterized and discussed. Additionally, a new stable dimer with methylmethylidene-hexahydropyrimidine structure was found in the S0 state.
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Affiliation(s)
- Mario Barbatti
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr (Germany).
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14
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Burggraf F, Koslowski T. Charge transfer through a cytochrome multiheme chain: Theory and simulation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:186-92. [DOI: 10.1016/j.bbabio.2013.09.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 08/22/2013] [Accepted: 09/10/2013] [Indexed: 10/26/2022]
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Abstract
Photoinduced processes in nucleic acids are phenomena of fundamental interest in diverse fields, from prebiotic studies, through medical research on carcinogenesis, to the development of bioorganic photodevices. In this contribution we survey many aspects of the research across the boundaries. Starting from a historical background, where the main milestones are identified, we review the main findings of the physical-chemical research of photoinduced processes on several types of nucleic-acid fragments, from monomers to duplexes. We also discuss a number of different issues which are still under debate.
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Affiliation(s)
- Mario Barbatti
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany,
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16
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Biskup T. Time-resolved electron paramagnetic resonance of radical pair intermediates in cryptochromes. Mol Phys 2013. [DOI: 10.1080/00268976.2013.833350] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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17
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Schill M, Koslowski T. Sensing organic molecules by charge transfer through aptamer-target complexes: theory and simulation. J Phys Chem B 2013; 117:475-83. [PMID: 23227783 DOI: 10.1021/jp308042n] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Aptamers, i.e., short sequences of RNA and single-stranded DNA, are capable of specificilly binding objects ranging from small molecules over proteins to entire cells. Here, we focus on the structure, stability, dynamics, and electronic properties of oligonucleotides that interact with aromatic or heterocyclic targets. Large-scale molecular dynamics simulations indicate that aromatic rings such as dyes, metabolites, or alkaloides form stable adducts with their oligonucleotide host molecules at least on the simulation time scale. From molecular dynamics snapshots, the energy parameters relevant to Marcus' theory of charge transfer are computed using a modified Su-Schrieffer-Heeger Hamiltonian, permitting an estimate of the charge transfer rates. In many cases, aptamer binding seriously influences the charge transfer kinetics and the charge carrier mobility within the complex, with conductivities up to the nanoampere range for a single complex. We discuss the conductivity properties with reference to potential applications as biosensors.
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Affiliation(s)
- Maria Schill
- Institut für Physikalische Chemie, Universität Freiburg, Albertstrasse 23a, D-79104 Freiburg im Breisgau, Germany
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