1
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Tamez A, Nilsson L, Mihailescu MR, Evanseck JD. Parameterization of the miniPEG-Modified γPNA Backbone: Toward Induced γPNA Duplex Dissociation. J Chem Theory Comput 2023. [PMID: 37195939 DOI: 10.1021/acs.jctc.2c01163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
γ-Modified peptide nucleic acids (γPNAs) serve as potential therapeutic agents against genetic diseases. Miniature poly(ethylene glycol) (miniPEG) has been reported to increase solubility and binding affinity toward genetic targets, yet details of γPNA structure and dynamics are not understood. Within our work, we parameterized missing torsional and electrostatic terms for the miniPEG substituent on the γ-carbon atom of the γPNA backbone in the CHARMM force field. Microsecond timescale molecular dynamics simulations were carried out on six miniPEG-modified γPNA duplexes from NMR structures (PDB ID: 2KVJ). Three NMR models for the γPNA duplex (PDB ID: 2KVJ) were simulated as a reference for structural and dynamic changes captured for the miniPEG-modified γPNA duplex. Principal component analysis performed on the γPNA backbone atoms identified a single isotropic conformational substate (CS) for the NMR simulations, whereas four anisotropic CSs were identified for the ensemble of miniPEG-modified γPNA simulations. The NMR structures were found to have a 23° helical bend toward the major groove, consistent with our simulated CS structure of 19.0°. However, a significant difference between simulated methyl- and miniPEG-modified γPNAs involved the opportunistic invasion of miniPEG through the minor and major groves. Specifically, hydrogen bond fractional analysis showed that the invasion was particularly prone to affect the second G-C base pair, reducing the Watson-Crick base pair hydrogen bond by 60% over the six simulations, whereas the A-T base pairs decreased by only 20%. Ultimately, the invasion led to base stack reshuffling, where the well-ordered base stacking was reduced to segmented nucleobase stacking interactions. Our 6 μs timescale simulations indicate that duplex dissociation suggests the onset toward γPNA single strands, consistent with the experimental observation of decreased aggregation. To complement the insight of miniPEG-modified γPNA structure and dynamics, the new miniPEG force field parameters allow for further exploration of such modified γPNA single strands as potential therapeutic agents against genetic diseases.
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Affiliation(s)
- Angel Tamez
- Center for Computational Sciences and the Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282, United States
| | - Lennart Nilsson
- Department of Biosciences and Nutrition, Karolinska Institute, Solnavägen 1, 171 77 Solna, Sweden
| | - Mihaela-Rita Mihailescu
- Center for Computational Sciences and the Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282, United States
| | - Jeffrey D Evanseck
- Center for Computational Sciences and the Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282, United States
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2
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Zheng Z, Kim SH, Chovin A, Clement N, Demaille C. Electrochemical response of surface-attached redox DNA governed by low activation energy electron transfer kinetics. Chem Sci 2023; 14:3652-3660. [PMID: 37006693 PMCID: PMC10055828 DOI: 10.1039/d3sc00320e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 03/07/2023] [Indexed: 03/16/2023] Open
Abstract
We demonstrate, using high scan rate cyclic voltammetry and molecular dynamics simulations, that the electrochemical response of electrode-attached redox DNA is governed by low reorganization energy electron transfer kinetics.
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Affiliation(s)
- Zhiyong Zheng
- Université Paris Cité, CNRS, Laboratoire d'Electrochimie Moléculaire, F-75013 Paris, France
| | - Soo Hyeon Kim
- IIS, LIMMS/CNRS-IIS UMI2820, The Univ. of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505, Japan
| | - Arnaud Chovin
- Université Paris Cité, CNRS, Laboratoire d'Electrochimie Moléculaire, F-75013 Paris, France
| | - Nicolas Clement
- IIS, LIMMS/CNRS-IIS UMI2820, The Univ. of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505, Japan
| | - Christophe Demaille
- Université Paris Cité, CNRS, Laboratoire d'Electrochimie Moléculaire, F-75013 Paris, France
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3
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Mohammad H, Demir B, Akin C, Luan B, Hihath J, Oren EE, Anantram MP. Role of intercalation in the electrical properties of nucleic acids for use in molecular electronics. NANOSCALE HORIZONS 2021; 6:651-660. [PMID: 34190284 DOI: 10.1039/d1nh00211b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Intercalating ds-DNA/RNA with small molecules can play an essential role in controlling the electron transmission probability for molecular electronics applications such as biosensors, single-molecule transistors, and data storage. However, its applications are limited due to a lack of understanding of the nature of intercalation and electron transport mechanisms. We addressed this long-standing problem by studying the effect of intercalation on both the molecular structure and charge transport along the nucleic acids using molecular dynamics simulations and first-principles calculations coupled with the Green's function method, respectively. The study on anthraquinone and anthraquinone-neomycin conjugate intercalation into short nucleic acids reveals some universal features: (1) the intercalation affects the transmission by two mechanisms: (a) inducing energy levels within the bandgap and (b) shifting the location of the Fermi energy with respect to the molecular orbitals of the nucleic acid, (2) the effect of intercalation was found to be dependent on the redox state of the intercalator: while oxidized anthraquinone decreases, reduced anthraquinone increases the conductance, and (3) the sequence of the intercalated nucleic acid further affects the transmission: lowering the AT-region length was found to enhance the electronic coupling of the intercalator with GC bases, hence yielding an increase of more than four times in conductance. We anticipate our study to inspire designing intercalator-nucleic acid complexes for potential use in molecular electronics via creating a multi-level gating effect.
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Affiliation(s)
- Hashem Mohammad
- Department of Electrical Engineering, University of Washington, Seattle, WA, USA.
| | - Busra Demir
- Bionanodesign Laboratory, Department of Biomedical Engineering, TOBB University of Economics and Technology, Ankara, Turkey. and Department of Materials Science & Nanotechnology Engineering, TOBB University of Economics and Technology, Ankara, Turkey
| | - Caglanaz Akin
- Bionanodesign Laboratory, Department of Biomedical Engineering, TOBB University of Economics and Technology, Ankara, Turkey. and Department of Materials Science & Nanotechnology Engineering, TOBB University of Economics and Technology, Ankara, Turkey
| | - Binquan Luan
- Computational Biological Center, IBM Thomas J. Watson Research, Yorktown Heights, NY 10598, USA
| | - Joshua Hihath
- Electrical and Computer Engineering Department, University of California Davis, Davis, CA, USA
| | - Ersin Emre Oren
- Bionanodesign Laboratory, Department of Biomedical Engineering, TOBB University of Economics and Technology, Ankara, Turkey. and Department of Materials Science & Nanotechnology Engineering, TOBB University of Economics and Technology, Ankara, Turkey
| | - M P Anantram
- Department of Electrical Engineering, University of Washington, Seattle, WA, USA.
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4
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Horsley JR, Wang X, Yu J, Abell AD. Exploiting conformationally gated electron transfer in self-assembled azobenzene-containing cyclic peptides using light. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.138232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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5
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Valdiviezo J, Clever C, Beall E, Pearse A, Bae Y, Zhang P, Achim C, Beratan DN, Waldeck DH. Delocalization-Assisted Transport through Nucleic Acids in Molecular Junctions. Biochemistry 2021; 60:1368-1378. [PMID: 33870693 DOI: 10.1021/acs.biochem.1c00072] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The flow of charge through molecules is central to the function of supramolecular machines, and charge transport in nucleic acids is implicated in molecular signaling and DNA repair. We examine the transport of electrons through nucleic acids to understand the interplay of resonant and nonresonant charge carrier transport mechanisms. This study reports STM break junction measurements of peptide nucleic acids (PNAs) with a G-block structure and contrasts the findings with previous results for DNA duplexes. The conductance of G-block PNA duplexes is much higher than that of the corresponding DNA duplexes of the same sequence; however, they do not display the strong even-odd dependence conductance oscillations found in G-block DNA. Theoretical analysis finds that the conductance oscillation magnitude in PNA is suppressed because of the increased level of electronic coupling interaction between G-blocks in PNA and the stronger PNA-electrode interaction compared to that in DNA duplexes. The strong interactions in the G-block PNA duplexes produce molecular conductances as high as 3% G0, where G0 is the quantum of conductance, for 5 nm duplexes.
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Affiliation(s)
- Jesús Valdiviezo
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Caleb Clever
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Edward Beall
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Alexander Pearse
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Yookyung Bae
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Peng Zhang
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Catalina Achim
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - David N Beratan
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States.,Department of Physics, Duke University, Durham, North Carolina 27708, United States.,Department of Biochemistry, Duke University, Durham, North Carolina 27710, United States
| | - David H Waldeck
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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6
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Mantela M, Morphis A, Lambropoulos K, Simserides C, Di Felice R. Effects of Structural Dynamics on Charge Carrier Transfer in B-DNA: A Combined MD and RT-TDDFT Study. J Phys Chem B 2021; 125:3986-4003. [PMID: 33857373 DOI: 10.1021/acs.jpcb.0c11489] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Hole transfer along the axis of duplex DNA has been the focus of physical chemistry research for decades, with implications in diverse fields, from nanotechnology to cell oxidative damage. Computational approaches are particularly amenable for this problem, to complement experimental data for interpretation of transfer mechanisms. To be predictive, computational results need to account for the inherent mobility of biological molecules during the time frame of experimental measurements. Here, we address the structural variability of B-DNA and its effects on hole transfer in a combined molecular dynamics (MD) and real-time time-dependent density functional theory (RT-TDDFT) study. Our results show that quantities that characterize the charge transfer process, such as the time-dependent dipole moment and hole population at a specific site, are sensitive to structural changes that occur on the nanosecond time scale. We extend the range of physical properties for which such a correlation has been observed, further establishing the fact that quantitative computational data on charge transfer properties should include statistical averages. Furthermore, we use the RT-TDDFT results to assess an efficient tight-binding method suitable for high-throughput predictions. We demonstrate that charge transfer, although affected by structural variability, on average, remains strong in AA and GG dimers.
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Affiliation(s)
- Marilena Mantela
- Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos GR-15784, Athens, Greece
| | - Andreas Morphis
- Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos GR-15784, Athens, Greece
| | - Konstantinos Lambropoulos
- Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos GR-15784, Athens, Greece
| | - Constantinos Simserides
- Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos GR-15784, Athens, Greece
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7
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Gamble Jarvi A, Sargun A, Bogetti X, Wang J, Achim C, Saxena S. Development of Cu 2+-Based Distance Methods and Force Field Parameters for the Determination of PNA Conformations and Dynamics by EPR and MD Simulations. J Phys Chem B 2020; 124:7544-7556. [PMID: 32790374 DOI: 10.1021/acs.jpcb.0c05509] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Peptide nucleic acids (PNAs) are a promising group of synthetic analogues of DNA and RNA that offer several distinct advantages over the naturally occurring nucleic acids for applications in biosensing, drug delivery, and nanoelectronics. Because of its structural differences from DNA/RNA, methods to analyze and assess the structure, conformations, and dynamics are needed. In this work, we develop synergistic techniques for the study of the PNA conformation. We use CuQ2, a Cu2+ complex with 8-hydroxyquinoline (HQ), as an alternative base pair and as a spin label in electron paramagnetic resonance (EPR) distance methods. We use molecular dynamics (MD) simulations with newly developed force field parameters for the spin labels to interpret the distance constraints determined by EPR. We complement these methods by UV-vis and circular dichroism measurements and assess the efficacy of the Cu2+ label on a PNA duplex whose backbone is based on aminoethylglycine and a duplex with a hydroxymethyl backbone modification. We show that the Cu2+ label functions efficiently within the standard PNA and the hydroxymethyl-modified PNA and that the MD parameters may be used to accurately reproduce our EPR findings. Through the combination of EPR and MD, we gain new insights into the PNA structure and conformations as well as into the mechanism of orientational selectivity in Cu2+ EPR at X-band. These results present for the first time a rigid Cu2+ spin label used for EPR distance measurements in PNA and the accompanying MD force fields for the spin label. Our studies also reveal that the spin labels have a low impact on the structure of the PNA duplexes. The combined MD and EPR approach represents an important new tool for the characterization of the PNA duplex structure and provides valuable information to aid in the rational application of PNA at large.
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Affiliation(s)
- Austin Gamble Jarvi
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Artur Sargun
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Xiaowei Bogetti
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Junmei Wang
- Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15206, United States
| | - Catalina Achim
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Sunil Saxena
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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8
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Skonieczny K, Espinoza EM, Derr JB, Morales M, Clinton JM, Xia B, Vullev VI. Biomimetic and bioinspired molecular electrets. How to make them and why does the established peptide chemistry not always work? PURE APPL CHEM 2020. [DOI: 10.1515/pac-2019-0111] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract“Biomimetic” and “bioinspired” define different aspects of the impacts that biology exerts on science and engineering. Biomimicking improves the understanding of how living systems work, and builds tools for bioinspired endeavors. Biological inspiration takes ideas from biology and implements them in unorthodox manners, exceeding what nature offers. Molecular electrets, i.e. systems with ordered electric dipoles, are key for advancing charge-transfer (CT) science and engineering. Protein helices and their biomimetic analogues, based on synthetic polypeptides, are the best-known molecular electrets. The inability of native polypeptide backbones to efficiently mediate long-range CT, however, limits their utility. Bioinspired molecular electrets based on anthranilamides can overcome the limitations of their biological and biomimetic counterparts. Polypeptide helices are easy to synthesize using established automated protocols. These protocols, however, fail to produce even short anthranilamide oligomers. For making anthranilamides, the residues are introduced as their nitrobenzoic-acid derivatives, and the oligomers are built from their C- to their N-termini via amide-coupling and nitro-reduction steps. The stringent requirements for these reduction and coupling steps pose non-trivial challenges, such as high selectivity, quantitative yields, and fast completion under mild conditions. Addressing these challenges will provide access to bioinspired molecular electrets essential for organic electronics and energy conversion.
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Affiliation(s)
- Kamil Skonieczny
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44-52, 01-224 Warsaw, Poland
| | - Eli M. Espinoza
- Department of Chemistry, University of California, Riverside, CA 92521, USA
| | - James B. Derr
- Department of Biochemistry, University of California, Riverside, CA 92521, USA
| | - Maryann Morales
- Department of Chemistry, University of California, Riverside, CA 92521, USA
| | - Jillian M. Clinton
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
| | - Bing Xia
- GlaxoSmithKline, 200 Cambridgepark Dr., Cambridge, MA 02140, USA
| | - Valentine I. Vullev
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
- Department of Chemistry, University of California, Riverside, CA 92521, USA
- Department of Biochemistry, University of California, Riverside, CA 92521, USA
- Materials Science and Engineering Program, University of California, Riverside, CA 92521, USA
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9
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Yu J, Horsley JR, Abell AD. Unravelling electron transfer in peptide-cation complexes: a model for mimicking redox centres in proteins. Phys Chem Chem Phys 2020; 22:8409-8417. [DOI: 10.1039/d0cp00635a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We provide evidence that bound zinc promotes electron transfer in a peptide by changing the electronic properties of the peptide.
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Affiliation(s)
- Jingxian Yu
- ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP)
- Institute of Photonics and Advanced Sensing (IPAS)
- Department of Chemistry
- The University of Adelaide
- Adelaide
| | - John R. Horsley
- ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP)
- Institute of Photonics and Advanced Sensing (IPAS)
- Department of Chemistry
- The University of Adelaide
- Adelaide
| | - Andrew D. Abell
- ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP)
- Institute of Photonics and Advanced Sensing (IPAS)
- Department of Chemistry
- The University of Adelaide
- Adelaide
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10
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Derr JB, Tamayo J, Espinoza EM, Clark JA, Vullev VI. Dipole-induced effects on charge transfer and charge transport. Why do molecular electrets matter? CAN J CHEM 2018. [DOI: 10.1139/cjc-2017-0389] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Charge transfer (CT) and charge transport (CTr) are at the core of life-sustaining biological processes and of processes that govern the performance of electronic and energy-conversion devices. Electric fields are invaluable for guiding charge movement. Therefore, as electrostatic analogues of magnets, electrets have unexplored potential for generating local electric fields for accelerating desired CT processes and suppressing undesired ones. The notion about dipole-generated local fields affecting CT has evolved since the middle of the 20th century. In the 1990s, the first reports demonstrating the dipole effects on the kinetics of long-range electron transfer appeared. Concurrently, the development of molecular-level designs of electric junctions has led the exploration of dipole effects on CTr. Biomimetic molecular electrets such as polypeptide helices are often the dipole sources in CT systems. Conversely, surface-charge electrets and self-assembled monolayers of small polar conjugates are the preferred sources for modifying interfacial electric fields for controlling CTr. The multifaceted complexity of such effects on CT and CTr testifies for the challenges and the wealth of this field that still remains largely unexplored. This review outlines the basic concepts about dipole effects on CT and CTr, discusses their evolution, and provides accounts for their future developments and impacts.
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Affiliation(s)
- James B. Derr
- Department of Biochemistry, University of California, Riverside, CA 92521, USA
| | - Jesse Tamayo
- Department of Chemistry, University of California, Riverside, CA 92521, USA
| | - Eli M. Espinoza
- Department of Chemistry, University of California, Riverside, CA 92521, USA
| | - John A. Clark
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
| | - Valentine I. Vullev
- Department of Biochemistry, University of California, Riverside, CA 92521, USA
- Department of Chemistry, University of California, Riverside, CA 92521, USA
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
- Materials Science and Engineering Program, University of California, Riverside, CA 92521, USA
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11
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Jasiński M, Feig M, Trylska J. Improved Force Fields for Peptide Nucleic Acids with Optimized Backbone Torsion Parameters. J Chem Theory Comput 2018; 14:3603-3620. [PMID: 29791152 DOI: 10.1021/acs.jctc.8b00291] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Peptide nucleic acids are promising nucleic acid analogs for antisense therapies as they can form stable duplex and triplex structures with DNA and RNA. Computational studies of PNA-containing duplexes and triplexes are an important component for guiding their design, yet existing force fields have not been well validated and parametrized with modern computational capabilities. We present updated CHARMM and Amber force fields for PNA that greatly improve the stability of simulated PNA-containing duplexes and triplexes in comparison with experimental structures and allow such systems to be studied on microsecond time scales. The force field modifications focus on reparametrized PNA backbone torsion angles to match high-level quantum mechanics reference energies for a model compound. The microsecond simulations of PNA-PNA, PNA-DNA, PNA-RNA, and PNA-DNA-PNA complexes also allowed a comprehensive analysis of hydration and ion interactions with such systems.
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Affiliation(s)
- Maciej Jasiński
- Department of Biochemistry and Molecular Biology , Michigan State University , East Lansing , Michigan 48824 , United States.,Centre of New Technologies , University of Warsaw , Warsaw , Poland
| | - Michael Feig
- Department of Biochemistry and Molecular Biology , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Joanna Trylska
- Centre of New Technologies , University of Warsaw , Warsaw , Poland
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12
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Maitarad A, Poomsuk N, Vilaivan C, Vilaivan T, Siriwong K. Insight into a conformation of the PNA-PNA duplex with (2′R,4′R)- and (2′R,4′S)-prolyl-(1S,2S)-2-aminocyclopentanecarboxylic acid backbones. Chem Phys Lett 2018. [DOI: 10.1016/j.cplett.2018.03.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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13
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Beall E, Ulku S, Liu C, Wierzbinski E, Zhang Y, Bae Y, Zhang P, Achim C, Beratan DN, Waldeck DH. Effects of the Backbone and Chemical Linker on the Molecular Conductance of Nucleic Acid Duplexes. J Am Chem Soc 2017; 139:6726-6735. [PMID: 28434220 DOI: 10.1021/jacs.7b02260] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Scanning tunneling microscope break junction measurements are used to examine how the molecular conductance of nucleic acids depends on the composition of their backbone and the linker group to the electrodes. Molecular conductances of 10 base pair long homoduplexes of DNA, aeg-PNA, γ-PNA, and a heteroduplex of DNA/aeg-PNA with identical nucleobase sequence were measured. The molecular conductance was found to vary by 12 to 13 times with the change in backbone. Computational studies show that the molecular conductance differences between nucleic acids of different backbones correlate with differences in backbone structural flexibility. The molecular conductance was also measured for duplexes connected to the electrode through two different linkers, one directly to the backbone and one directly to the nucleobase stack. While the linker causes an order-of-magnitude increase in the overall conductance for a particular duplex, the differences in the electrical conductance with backbone composition are preserved. The highest molecular conductance value, 0.06G0, was measured for aeg-PNA duplexes with a base stack linker. These findings reveal an important new strategy for creating longer and more complex electroactive, nucleic acid assemblies.
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Affiliation(s)
- Edward Beall
- Chemistry Department, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Selma Ulku
- Chemistry Department, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
| | - Chaoren Liu
- Chemistry Department, Duke University , Durham, North Carolina 27708, United States
| | - Emil Wierzbinski
- Chemistry Department, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Yuqi Zhang
- Chemistry Department, Duke University , Durham, North Carolina 27708, United States
| | - Yookyung Bae
- Chemistry Department, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
| | - Peng Zhang
- Chemistry Department, Duke University , Durham, North Carolina 27708, United States
| | - Catalina Achim
- Chemistry Department, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
| | - David N Beratan
- Chemistry Department, Duke University , Durham, North Carolina 27708, United States
| | - David H Waldeck
- Chemistry Department, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
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14
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Verona MD, Verdolino V, Palazzesi F, Corradini R. Focus on PNA Flexibility and RNA Binding using Molecular Dynamics and Metadynamics. Sci Rep 2017; 7:42799. [PMID: 28211525 PMCID: PMC5314342 DOI: 10.1038/srep42799] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 01/13/2017] [Indexed: 12/20/2022] Open
Abstract
Peptide Nucleic Acids (PNAs) can efficiently target DNA or RNA acting as chemical tools for gene regulation. Their backbone modification and functionalization is often used to increase the affinity for a particular sequence improving selectivity. The understanding of the trading forces that lead the single strand PNA to bind the DNA or RNA sequence is preparatory for any further rational design, but a clear and unique description of this process is still not complete. In this paper we report further insights into this subject, by a computational investigation aiming at the characterization of the conformations of a single strand PNA and how these can be correlated to its capability in binding DNA/RNA. Employing Metadynamics we were able to better define conformational pre-organizations of the single strand PNA and γ-modified PNA otherwise unrevealed through classical molecular dynamics. Our simulations driven on backbone modified PNAs lead to the conclusion that this γ-functionalization affects the single strand preorganization and targeting properties to the DNA/RNA, in agreement with circular dichroism (CD) spectra obtained for this class of compounds. MD simulations on PNA:RNA dissociation and association mechanisms allowed to reveal the critical role of central bases and preorganization in the binding process.
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Affiliation(s)
| | - Vincenzo Verdolino
- Department of Chemistry and Applied Biosciences, ETH Zurich, c/o Università della Svizzera Italiana Campus, 6900 Lugano, Switzerland
- Facoltà di Informatica, Instituto di Scienze Computazionali, Università della Svizzera Italiana, 6900 Lugano, Switzerland
| | - Ferruccio Palazzesi
- Department of Chemistry and Applied Biosciences, ETH Zurich, c/o Università della Svizzera Italiana Campus, 6900 Lugano, Switzerland
- Facoltà di Informatica, Instituto di Scienze Computazionali, Università della Svizzera Italiana, 6900 Lugano, Switzerland
| | - Roberto Corradini
- Dipartimento di Chimica, University of Parma, Italy, 43124, Italy
- National Institute for Biostructures and Biosystems (INBB)-Viale delle Medaglie d’Oro, 305, 00136 Roma, Italy
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15
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Guo C, Yu X, Refaely-Abramson S, Sepunaru L, Bendikov T, Pecht I, Kronik L, Vilan A, Sheves M, Cahen D. Tuning electronic transport via hepta-alanine peptides junction by tryptophan doping. Proc Natl Acad Sci U S A 2016; 113:10785-90. [PMID: 27621456 PMCID: PMC5047155 DOI: 10.1073/pnas.1606779113] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Charge migration for electron transfer via the polypeptide matrix of proteins is a key process in biological energy conversion and signaling systems. It is sensitive to the sequence of amino acids composing the protein and, therefore, offers a tool for chemical control of charge transport across biomaterial-based devices. We designed a series of linear oligoalanine peptides with a single tryptophan substitution that acts as a "dopant," introducing an energy level closer to the electrodes' Fermi level than that of the alanine homopeptide. We investigated the solid-state electron transport (ETp) across a self-assembled monolayer of these peptides between gold contacts. The single tryptophan "doping" markedly increased the conductance of the peptide chain, especially when its location in the sequence is close to the electrodes. Combining inelastic tunneling spectroscopy, UV photoelectron spectroscopy, electronic structure calculations by advanced density-functional theory, and dc current-voltage analysis, the role of tryptophan in ETp is rationalized by charge tunneling across a heterogeneous energy barrier, via electronic states of alanine and tryptophan, and by relatively efficient direct coupling of tryptophan to a Au electrode. These results reveal a controlled way of modulating the electrical properties of molecular junctions by tailor-made "building block" peptides.
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Affiliation(s)
- Cunlan Guo
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel 76100; Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel 76100
| | - Xi Yu
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel 76100
| | - Sivan Refaely-Abramson
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel 76100
| | - Lior Sepunaru
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel 76100; Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel 76100
| | - Tatyana Bendikov
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel 76100
| | - Israel Pecht
- Department of Immunology, Weizmann Institute of Science, Rehovot, Israel 76100
| | - Leeor Kronik
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel 76100
| | - Ayelet Vilan
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel 76100
| | - Mordechai Sheves
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel 76100
| | - David Cahen
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel 76100;
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16
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Liu C, Beratan DN, Zhang P. Coarse-Grained Theory of Biological Charge Transfer with Spatially and Temporally Correlated Noise. J Phys Chem B 2016; 120:3624-33. [DOI: 10.1021/acs.jpcb.6b01018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Chaoren Liu
- Department
of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - David N. Beratan
- Department
of Chemistry, Duke University, Durham, North Carolina 27708, United States
- Departments
of Biochemistry and Physics, Duke University, Durham, North Carolina 27708, United States
| | - Peng Zhang
- Department
of Chemistry, Duke University, Durham, North Carolina 27708, United States
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17
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Ghobadi AF, Jayaraman A. Effect of backbone chemistry on hybridization thermodynamics of oligonucleic acids: a coarse-grained molecular dynamics simulation study. SOFT MATTER 2016; 12:2276-87. [PMID: 26777980 DOI: 10.1039/c5sm02868j] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
In this paper we study how varying oligonucleic acid backbone chemistry affects the hybridization/melting thermodynamics of oligonucleic acids. We first describe the coarse-grained (CG) model with tunable parameters that we developed to enable the study of both naturally occurring oligonucleic acids, such as DNA, and their chemically-modified analogues, such as peptide nucleic acids (PNAs) and locked nucleic acids (LNAs). The DNA melting curves obtained using such a CG model and molecular dynamics simulations in an implicit solvent and with explicit ions match with the melting curves obtained using the empirical nearest-neighbor models. We use these CG simulations to then elucidate the effect of backbone flexibility, charge, and nucleobase spacing along the backbone on the melting curves, potential energy and conformational entropy change upon hybridization and base-pair hydrogen bond residence time. We find that increasing backbone flexibility decreases duplex thermal stability and melting temperature mainly due to increased conformational entropy loss upon hybridization. Removing charges from the backbone enhances duplex thermal stability due to the elimination of electrostatic repulsion and as a result a larger energetic gain upon hybridization. Lastly, increasing nucleobase spacing decreases duplex thermal stability due to decreasing stacking interactions that are important for duplex stability.
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Affiliation(s)
- Ahmadreza F Ghobadi
- Department of Chemical and Biomolecular Engineering, Colburn Laboratory, University of Delaware, 150 Academy Street, Newark, DE 19716, USA.
| | - Arthi Jayaraman
- Department of Chemical and Biomolecular Engineering, Colburn Laboratory, University of Delaware, 150 Academy Street, Newark, DE 19716, USA. and Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716, USA
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18
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Sun W, Shao M, Ren H, Xiao D, Qin X, Deng L, Chen X, Gao J. A New Type of Electron Relay Station in Proteins: Three-Piece S:Π∴S↔S∴Π:S Resonance Structure. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2015; 119:6998-7005. [PMID: 26113884 PMCID: PMC4476553 DOI: 10.1021/jp512628x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A type of relay station for electron transfer in proteins, three-piece five-electron bonding, is introduced in this paper, which is also first proposed here. The ab initio calculations predict the formation of S:Π∴S↔S∴Π:S resonance binding with an aromatic ring located in the middle of two sulfur-containing groups, which may participate in electron-hole transport in proteins. These special structures can lower the local ionization energies to capture electron holes efficiently and may be easily formed and broken because of their proper binding energies. In addition, the UV-vis spectra provide evidence of the formations of the three-piece five-electron binding. The cooperation of three adjacent pieces may be advantage to promote electron transfer a longer distance.
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Affiliation(s)
- Weichao Sun
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 400030, People’s Republic of China
| | - Mengyao Shao
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 400030, People’s Republic of China
| | - Haisheng Ren
- Department of Chemistry and Supercomputing Institute University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Dong Xiao
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 400030, People’s Republic of China
| | - Xin Qin
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 400030, People’s Republic of China
| | - Li Deng
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 400030, People’s Republic of China
| | - Xiaohua Chen
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 400030, People’s Republic of China
- Department of Chemistry and Supercomputing Institute University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Jiali Gao
- Department of Chemistry and Supercomputing Institute University of Minnesota, Minneapolis, Minnesota 55455, United States
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19
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20
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Autiero I, Saviano M, Langella E. Conformational studies of chiral D-Lys-PNA and achiral PNA system in binding with DNA or RNA through a molecular dynamics approach. Eur J Med Chem 2014; 91:109-17. [PMID: 25112690 DOI: 10.1016/j.ejmech.2014.08.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 07/31/2014] [Accepted: 08/01/2014] [Indexed: 12/23/2022]
Abstract
The growing interest in peptide nucleic acid (PNA) oligomers has led to the development of a very wide variety of PNA derivatives. Among others, the introduction of charged chiral groups on a PNA oligomer has proven effective in improving DNA binding ability, complexation direction and cellular uptake. In particular, the introduction of three adjacent chiral monomers based on D-Lys in the middle of the PNA sequence (D-Lys-PNA) has produced noteworthy results in modulating the directionality of the binding with the DNA complementary strand and in mismatch detection. Here, through a molecular dynamics approach, a comparative study has been carried out to investigate the structural properties that drive the interaction of the chiral D-Lys-PNA and the corresponding achiral PNA system with DNA as well as RNA complementary strands, starting from the crystal structure of D-Lys-PNA in complex with DNA. The results obtained complement experimental data and indicate that the binding with the RNA molecule, compared to DNA, is differently affected by the addition of three D-Lys groups on the PNA backbone, suggesting that this modification could be taken into account for the development of new PNA-based molecules able to discriminate between DNA and RNA.
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Affiliation(s)
- Ida Autiero
- National Research Council, Institute of Biostructures and Bioimaging, 80134 Naples, Italy
| | - Michele Saviano
- National Research Council, Institute of Crystallography, 70126 Bari, Italy.
| | - Emma Langella
- National Research Council, Institute of Biostructures and Bioimaging, 80134 Naples, Italy.
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21
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Yin X, Kong J, De Leon A, Li Y, Ma Z, Wierzbinski E, Achim C, Waldeck DH. Luminescence quenching by photoinduced charge transfer between metal complexes in peptide nucleic acids. J Phys Chem B 2014; 118:9037-45. [PMID: 24975518 DOI: 10.1021/jp5027042] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A new scaffold for studying photoinduced charge transfer has been constructed by connecting a [Ru(Bpy)3](2+) donor to a bis(8-hydroxyquinolinate)2 copper [CuQ2] acceptor through a peptide nucleic acid (PNA) bridge. The luminescence of the [Ru(Bpy)3](2+*) donor is quenched by electron transfer to the [CuQ2] acceptor. Photoluminescence studies of these donor-bridge-acceptor systems reveal a dependence of the charge transfer on the length and sequence of the PNA bridge and on the position of the donor and acceptor in the PNA. In cases where the [Ru(Bpy)3](2+) can access the π base stack at the terminus of the duplex, the luminescence decay is described well by a single exponential; but if the donor is sterically hindered from accessing the π base stack of the PNA duplex, a distribution of luminescence lifetimes for the donor [Ru(Bpy)3](2+*) is observed. Molecular dynamics simulations are used to explore the donor-PNA-acceptor structure and the resulting conformational distribution provides a possible explanation for the distribution of electron transfer rates.
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Affiliation(s)
- Xing Yin
- Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
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22
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Yin X, Wierzbinski E, Lu H, Bezer S, de Leon AR, Davis KL, Achim C, Waldeck DH. A three-step kinetic model for electrochemical charge transfer in the hopping regime. J Phys Chem A 2014; 118:7579-89. [PMID: 24813905 DOI: 10.1021/jp502826e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Single-step nonadiabatic electron tunneling models are widely used to analyze electrochemical rates through self-assembled monolayer films (SAMs). For some systems, such as nucleic acids, long-range charge transfer can occur in a "hopping" regime that involves multiple charge transfer events and intermediate states. This report describes a three-step kinetic scheme to model charge transfer in this regime. Some of the features of the three-step model are probed experimentally by changing the chemical composition of the SAM. This work uses the three-step model and a temperature dependence of the charge transfer rate to extract the charge injection barrier for a SAM composed of a 10-mer peptide nucleic acid that operates in the hopping regime.
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Affiliation(s)
- Xing Yin
- Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
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23
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Yu J, Horsley JR, Moore KE, . Shapter JG, Abell AD. The effect of a macrocyclic constraint on electron transfer in helical peptides: A step towards tunable molecular wires. Chem Commun (Camb) 2014; 50:1652-4. [DOI: 10.1039/c3cc47885h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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24
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Dynamics and efficiency of photoinduced charge transport in DNA: Toward the elusive molecular wire. PURE APPL CHEM 2013. [DOI: 10.1351/pac-con-13-01-09] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Experimental investigations of photoinduced charge transport in synthetic DNA
capped hairpins possessing electron acceptor and donor stilbene chromophores at
either end have established the mechanism, dynamics, and efficiency of charge
transport in DNA. The mechanism for charge transport in repeating A-T base pairs
(A-tracts) was found to change from single-step superexchange at short distances
to multistep incoherent hole hopping at longer distances. The rate constants for
base-to-base hole hopping in longer A- and G-tract sequences are 1.2
× 109 s–1 and 4.3 × 109 s–1,
respectively, considerably slower than the rate constants associated with
molecular wires. Even slower rate constants are observed for alternating or
random base sequences such as those encountered in natural DNA. The efficiency
of charge separation in capped hairpins with A-tract sequences is also low as a
consequence of the competition of hole hopping with charge recombination.
Significantly higher efficiencies for charge separation are possible using
diblock purine base sequences consisting of two or three adenines followed by a
larger number of guanines. The short A-block serves as a molecular rectifier,
slowing down charge recombination. More efficient charge separation can also be
achieved using non-natural bases or by using the triplet acceptor anthraquinone
for hole injection.
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25
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Lewis FD. Distance-Dependent Electronic Interactions Across DNA Base Pairs: Charge Transport, Exciton Coupling, and Energy Transfer. Isr J Chem 2013. [DOI: 10.1002/ijch.201300035] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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26
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Mie Y, Kowata K, Kojima N, Komatsu Y. Electrochemical properties of interstrand cross-linked DNA duplexes labeled with Nile blue. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:17211-17216. [PMID: 23153070 DOI: 10.1021/la3036538] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
DNA molecules have attracted considerable attention as functional materials in various fields such as electrochemical sensors with redox-labeled DNA. However, the recently developed interstrand cross-link (ICL) technique for double-stranded DNA can adequately modify the electronic properties inside the duplex. Hence, the electrochemical investigation of ICL-DNA helps us to understand the electron transfer of redox-labeled DNA at an electrode surface, which would develop useful sensors. In this study, the first insight into this matter is presented. We prepared 17-mer DNA duplexes incorporating Nile blue (NB-DNA) at one end as a redox marker and a disulfide tether at the other end for immobilization onto an electrode. The duplexes were covalently cross-linked by bifunctional cross-linkers that utilize either a propyl or naphthalene residue to replace a base pair. Their electrochemical responses at the electrode surface were compared to evaluate the effect of the ICL on the electron-transfer reactions of the redox-labeled DNA duplexes. A direct transfer of electrons between NB and the electrode was observed for a standard DNA, as previously reported, whereas interstrand cross-linked DNA (CL-DNA) strands showed a decrease in the direct electron-transfer pathway. This is expected to result from constraining the elastic bending/flexibility of the duplex caused by the covalent cross-links. Interestingly, the CL-DNA incorporating naphthalene residues exhibited additional voltammetric peaks derived from DNA-mediated electron transfer (through base π stacking), which was not observed in the mismatched CL-DNA. The present results indicate that the ICL significantly affects electron transfer in the redox-labeled DNA at the electrode and can be an important determinant for electrochemical signaling in addition to its role in stabilizing the duplex structure.
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Affiliation(s)
- Yasuhiro Mie
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-higashi, Toyohira, Sapporo 062-8517, Japan
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27
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Wierzbinski E, Yin X, Werling K, Waldeck DH. The Effect of Oxygen Heteroatoms on the Single Molecule Conductance of Saturated Chains. J Phys Chem B 2012; 117:4431-41. [DOI: 10.1021/jp307902v] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Emil Wierzbinski
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Xing Yin
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Keith Werling
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - David H. Waldeck
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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28
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Thazhathveetil AK, Vura-Weis J, Trifonov A, Wasielewski MR, Lewis FD. Dynamics and efficiency of hole transport in LNA:DNA hybrid diblock oligomers. J Am Chem Soc 2012; 134:16434-40. [PMID: 22958189 DOI: 10.1021/ja307989t] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We report here the effect of replacing one or both of the purine or pyrimidine blocks of a diblock stilbene donor-acceptor capped hairpin with locked nucleic acid (LNA) bases on the dynamics and efficiency of hole transport. The structures of the DNA and LNA:DNA hybrids are tentatively assigned to B- or A-type structures on the basis of their circular dichroism spectra. Replacing the bases in either the A-block or the G-block of the diblock DNA hairpin with LNA bases results in a modest decrease in the base-to-base hopping rate constant and quantum yield for charge separation. Somewhat larger decreases are observed when all of the purine or pyrimidine bases are replaced by LNA bases.
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Affiliation(s)
- Arun K Thazhathveetil
- Department of Chemistry and Argonne-Northwestern Solar Energy Research Center, Northwestern University, Evanston, Illinois 60208, USA
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