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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Goodman J, Attwood D, Kiely J, Coladas Mato P, Luxton R. Modeling Peptide Nucleic Acid Binding Enthalpies Using MM-GBSA. J Phys Chem B 2022; 126:9528-9538. [PMID: 36375178 PMCID: PMC9706560 DOI: 10.1021/acs.jpcb.2c05547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The binding enthalpies of peptide nucleic acid (PNA) homoduplexes were predicted using a molecular mechanics generalized Born surface area approach. Using the nucleic acid nearest-neighbor model, these were decomposed into sequence parameters which could replicate the enthalpies from thermal melting experiments with a mean error of 8.7%. These results present the first systematic computational investigation into the relationship between sequence and binding energy for PNA homoduplexes and identified a stabilizing helix initiation enthalpy not observed for nucleic acids with phosphoribose backbones.
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Affiliation(s)
- Jack Goodman
- University
of the West of England, BristolBS16 1QY, U.K.,
| | - David Attwood
- University
of the West of England, BristolBS16 1QY, U.K.
| | - Janice Kiely
- University
of the West of England, BristolBS16 1QY, U.K.
| | | | - Richard Luxton
- University
of the West of England, BristolBS16 1QY, U.K.
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3
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Mosseri A, Sancho‐Albero M, Leone M, Nava D, Secundo F, Maggioni D, De Cola L, Romanelli A. Chiral Fibers Formation Upon Assembly of Tetraphenylalanine Peptide Conjugated to a PNA Dimer. Chemistry 2022; 28:e202200693. [PMID: 35474351 PMCID: PMC9325372 DOI: 10.1002/chem.202200693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Indexed: 11/17/2022]
Abstract
Self‐assembly of biomolecules such as peptides, nucleic acids or their analogues affords supramolecular objects, exhibiting structures and physical properties dependent on the amino‐acid or nucleobase composition. Conjugation of the peptide diphenylalanine (FF) to peptide nucleic acids triggers formation of self‐assembled structures, mainly stabilized by interactions between FF. In this work we report formation of homogeneous chiral fibers upon self‐assembly of the hybrid composed of the tetraphenylalanine peptide (4F) conjugated to the PNA dimer adenine‐thymine (at). In this case nucleobases seem to play a key role in determining the morphology and chirality of the fibers. When the PNA “at” is replaced by guanine‐cytosine dimer “gc”, disordered structures are observed. Spectroscopic characterization of the self‐assembled hybrids, along with AFM and SEM studies is reported. Finally, a structural model consistent with the experimental evidence has also been obtained, showing how the building blocks of 4Fat arrange to give helical fibers.
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Affiliation(s)
- Andrea Mosseri
- Dipartimento di Scienze Farmaceutiche Università degli Studi di Milano via Venezian 21 20133 Milano Italy
| | - Maria Sancho‐Albero
- Department of Molecular Biochemistry and Pharmacology Istituto di Ricerche Farmacologiche Mario Negri IRCCS 20156 Milano Italy
| | - Marilisa Leone
- Istituto di Biostrutture e Bioimmagini – CNR via Mezzocannone 16 80134 Naples Italy
| | - Donatella Nava
- Dipartimento di Scienze Farmaceutiche Università degli Studi di Milano via Venezian 21 20133 Milano Italy
| | - Francesco Secundo
- Istituto di Scienze e Tecnologie Chimiche “Giulio Natta”, CNR via Mario Bianco 9 Milan 20131 Italy
| | - Daniela Maggioni
- Dipartimento di Chimica Università degli Studi di Milano Via Golgi 19 20133 Milano Italy
| | - Luisa De Cola
- Dipartimento di Scienze Farmaceutiche Università degli Studi di Milano via Venezian 21 20133 Milano Italy
- Department of Molecular Biochemistry and Pharmacology Istituto di Ricerche Farmacologiche Mario Negri IRCCS 20156 Milano Italy
| | - Alessandra Romanelli
- Dipartimento di Scienze Farmaceutiche Università degli Studi di Milano via Venezian 21 20133 Milano Italy
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4
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Suparpprom C, Vilaivan T. Perspectives on conformationally constrained peptide nucleic acid (PNA): insights into the structural design, properties and applications. RSC Chem Biol 2022; 3:648-697. [PMID: 35755191 PMCID: PMC9175113 DOI: 10.1039/d2cb00017b] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 03/17/2022] [Indexed: 11/21/2022] Open
Abstract
Peptide nucleic acid or PNA is a synthetic DNA mimic that contains a sequence of nucleobases attached to a peptide-like backbone derived from N-2-aminoethylglycine. The semi-rigid PNA backbone acts as a scaffold that arranges the nucleobases in a proper orientation and spacing so that they can pair with their complementary bases on another DNA, RNA, or even PNA strand perfectly well through the standard Watson-Crick base-pairing. The electrostatically neutral backbone of PNA contributes to its many unique properties that make PNA an outstanding member of the xeno-nucleic acid family. Not only PNA can recognize its complementary nucleic acid strand with high affinity, but it does so with excellent specificity that surpasses the specificity of natural nucleic acids and their analogs. Nevertheless, there is still room for further improvements of the original PNA in terms of stability and specificity of base-pairing, direction of binding, and selectivity for different types of nucleic acids, among others. This review focuses on attempts towards the rational design of new generation PNAs with superior performance by introducing conformational constraints such as a ring or a chiral substituent in the PNA backbone. A large collection of conformationally rigid PNAs developed during the past three decades are analyzed and compared in terms of molecular design and properties in relation to structural data if available. Applications of selected modified PNA in various areas such as targeting of structured nucleic acid targets, supramolecular scaffold, biosensing and bioimaging, and gene regulation will be highlighted to demonstrate how the conformation constraint can improve the performance of the PNA. Challenges and future of the research in the area of constrained PNA will also be discussed.
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Affiliation(s)
- Chaturong Suparpprom
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Naresuan University, Tah-Poe District, Muang Phitsanulok 65000 Thailand
- Organic Synthesis Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University Phayathai Road Pathumwan Bangkok 10330 Thailand
| | - Tirayut Vilaivan
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Naresuan University, Tah-Poe District, Muang Phitsanulok 65000 Thailand
- Organic Synthesis Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University Phayathai Road Pathumwan Bangkok 10330 Thailand
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5
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Zhu G, Song P, Wu J, Luo M, Chen Z, Chen T. Application of Nucleic Acid Frameworks in the Construction of Nanostructures and Cascade Biocatalysts: Recent Progress and Perspective. Front Bioeng Biotechnol 2022; 9:792489. [PMID: 35071205 PMCID: PMC8777461 DOI: 10.3389/fbioe.2021.792489] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Accepted: 12/10/2021] [Indexed: 12/12/2022] Open
Abstract
Nucleic acids underlie the storage and retrieval of genetic information literally in all living organisms, and also provide us excellent materials for making artificial nanostructures and scaffolds for constructing multi-enzyme systems with outstanding performance in catalyzing various cascade reactions, due to their highly diverse and yet controllable structures, which are well determined by their sequences. The introduction of unnatural moieties into nucleic acids dramatically increased the diversity of sequences, structures, and properties of the nucleic acids, which undoubtedly expanded the toolbox for making nanomaterials and scaffolds of multi-enzyme systems. In this article, we first introduce the molecular structures and properties of nucleic acids and their unnatural derivatives. Then we summarized representative artificial nanomaterials made of nucleic acids, as well as their properties, functions, and application. We next review recent progress on constructing multi-enzyme systems with nucleic acid structures as scaffolds for cascade biocatalyst. Finally, we discuss the future direction of applying nucleic acid frameworks in the construction of nanomaterials and multi-enzyme molecular machines, with the potential contribution that unnatural nucleic acids may make to this field highlighted.
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Affiliation(s)
- Gan Zhu
- MOE International Joint Research Laboratory on Synthetic Biology and Medicines, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Ping Song
- MOE International Joint Research Laboratory on Synthetic Biology and Medicines, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Jing Wu
- MOE International Joint Research Laboratory on Synthetic Biology and Medicines, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Minglan Luo
- MOE International Joint Research Laboratory on Synthetic Biology and Medicines, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Zhipeng Chen
- MOE International Joint Research Laboratory on Synthetic Biology and Medicines, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Tingjian Chen
- MOE International Joint Research Laboratory on Synthetic Biology and Medicines, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
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6
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Brodyagin N, Katkevics M, Kotikam V, Ryan CA, Rozners E. Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications. Beilstein J Org Chem 2021; 17:1641-1688. [PMID: 34367346 PMCID: PMC8313981 DOI: 10.3762/bjoc.17.116] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 06/28/2021] [Indexed: 12/23/2022] Open
Abstract
Peptide nucleic acid (PNA) is arguably one of the most successful DNA mimics, despite a most dramatic departure from the native structure of DNA. The present review summarizes 30 years of research on PNA's chemistry, optimization of structure and function, applications as probes and diagnostics, and attempts to develop new PNA therapeutics. The discussion starts with a brief review of PNA's binding modes and structural features, followed by the most impactful chemical modifications, PNA enabled assays and diagnostics, and discussion of the current state of development of PNA therapeutics. While many modifications have improved on PNA's binding affinity and specificity, solubility and other biophysical properties, the original PNA is still most frequently used in diagnostic and other in vitro applications. Development of therapeutics and other in vivo applications of PNA has notably lagged behind and is still limited by insufficient bioavailability and difficulties with tissue specific delivery. Relatively high doses are required to overcome poor cellular uptake and endosomal entrapment, which increases the risk of toxicity. These limitations remain unsolved problems waiting for innovative chemistry and biology to unlock the full potential of PNA in biomedical applications.
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Affiliation(s)
- Nikita Brodyagin
- Department of Chemistry, Binghamton University, The State University of New York, Binghamton, New York 13902, United States
| | - Martins Katkevics
- Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga, LV-1006, Latvia
| | - Venubabu Kotikam
- Department of Chemistry, Binghamton University, The State University of New York, Binghamton, New York 13902, United States
| | - Christopher A Ryan
- Department of Chemistry, Binghamton University, The State University of New York, Binghamton, New York 13902, United States
| | - Eriks Rozners
- Department of Chemistry, Binghamton University, The State University of New York, Binghamton, New York 13902, United States
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7
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Alenaizan A, Barnett JL, Hud NV, Sherrill CD, Petrov AS. The proto-Nucleic Acid Builder: a software tool for constructing nucleic acid analogs. Nucleic Acids Res 2021; 49:79-89. [PMID: 33300028 PMCID: PMC7797056 DOI: 10.1093/nar/gkaa1159] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 11/09/2020] [Accepted: 11/13/2020] [Indexed: 11/13/2022] Open
Abstract
The helical structures of DNA and RNA were originally revealed by experimental data. Likewise, the development of programs for modeling these natural polymers was guided by known structures. These nucleic acid polymers represent only two members of a potentially vast class of polymers with similar structural features, but that differ from DNA and RNA in the backbone or nucleobases. Xeno nucleic acids (XNAs) incorporate alternative backbones that affect the conformational, chemical, and thermodynamic properties of XNAs. Given the vast chemical space of possible XNAs, computational modeling of alternative nucleic acids can accelerate the search for plausible nucleic acid analogs and guide their rational design. Additionally, a tool for the modeling of nucleic acids could help reveal what nucleic acid polymers may have existed before RNA in the early evolution of life. To aid the development of novel XNA polymers and the search for possible pre-RNA candidates, this article presents the proto-Nucleic Acid Builder (https://github.com/GT-NucleicAcids/pnab), an open-source program for modeling nucleic acid analogs with alternative backbones and nucleobases. The torsion-driven conformation search procedure implemented here predicts structures with good accuracy compared to experimental structures, and correctly demonstrates the correlation between the helical structure and the backbone conformation in DNA and RNA.
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Affiliation(s)
- Asem Alenaizan
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA.,Center for Computational Molecular Science and Technology, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA
| | - Joshua L Barnett
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332-0430, USA
| | - Nicholas V Hud
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA
| | - C David Sherrill
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA.,Center for Computational Molecular Science and Technology, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA.,School of Computational Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0765, USA
| | - Anton S Petrov
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA
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8
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Möllers PV, Ulku S, Jayarathna D, Tassinari F, Nürenberg D, Naaman R, Achim C, Zacharias H. Spin-selective electron transmission through self-assembled monolayers of double-stranded peptide nucleic acid. Chirality 2021; 33:93-102. [PMID: 33400337 DOI: 10.1002/chir.23290] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/06/2020] [Accepted: 12/01/2020] [Indexed: 12/19/2022]
Abstract
Monolayers of chiral molecules can preferentially transmit electrons with a specific spin orientation, introducing chiral molecules as efficient spin filters. This phenomenon is established as chirality-induced spin selectivity (CISS) and was demonstrated directly for the first time in self-assembled monolayers (SAMs) of double-stranded DNA (dsDNA)1 . Here, we discuss SAMs of double-stranded peptide nucleic acid (dsPNA) as a system which allows for systematic investigations of the influence of various molecular properties on CISS. In photoemission studies, SAMs of chiral, γ-modified PNA show significant spin filtering of up to P = (24.4 ± 4.3)% spin polarization. The polarization values found in PNA lacking chiral monomers are considerably lower at about P = 12%. The results confirm that the preferred spin orientation is directly linked to the molecular handedness and indicate that the spin filtering capacity of the dsPNA helices might be enhanced by introduction of chiral centers in the constituting peptide monomers.
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Affiliation(s)
- Paul Valerian Möllers
- Center for Soft Nanoscience (SoN), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Selma Ulku
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Dilhara Jayarathna
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Francesco Tassinari
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Daniel Nürenberg
- Center for Soft Nanoscience (SoN), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Ron Naaman
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Catalina Achim
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Helmut Zacharias
- Center for Soft Nanoscience (SoN), Westfälische Wilhelms-Universität Münster, Münster, Germany
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9
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Moccia M, Mercurio FA, Langella E, Piacenti V, Leone M, Adamo MFA, Saviano M. Structural Insights on Tiny Peptide Nucleic Acid (PNA) Analogues of miRNA-34a: An in silico and Experimental Integrated Approach. Front Chem 2020; 8:568575. [PMID: 33330358 PMCID: PMC7719796 DOI: 10.3389/fchem.2020.568575] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 11/02/2020] [Indexed: 11/17/2022] Open
Abstract
In the present work, structural features of the interaction between peptide nucleic acid (PNA)-based analogs of the tumor-suppressor microRNA-34a with both its binding sites on MYCN mRNA were investigated. In particular, the region from base 1 to 8 ("seed" region) of miR-34a was reproduced in the form of an 8-mer PNA fragment (tiny PNA), and binding to target 3'UTR MYCN mRNA, was studied by a seldom reported and detailed NMR characterization, providing evidence for the formation of anti-parallel duplexes with a well-organized structural core. The formation of PNA-3'UTR duplexes was also confirmed by Circular Dichroism, and their melting curves were measured by UV spectroscopy. Nevertheless, this study offered a valuable comparison between molecular dynamics predictions and experimental evidence, which showed great correlation. Preliminary uptake assays were carried out in Neuroblastoma Kelly cells, using short peptide conjugates as carriers and FITC fluorescent tag for subcellular localization. Moderate internalization was observed without the use of transfecting agents. The reported results corroborate the interest toward the design and development of chimeric PNA/RNA sequences as effective RNA-targeting agents.
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Affiliation(s)
- Maria Moccia
- Institute of Crystallography, National Research Council, Department of Chemical Sciences and Materials Technologies, Bari, Italy
| | - Flavia Anna Mercurio
- Institute of Biostructures and Bioimaging, National Research Council, Naples, Italy
| | - Emma Langella
- Institute of Biostructures and Bioimaging, National Research Council, Naples, Italy
| | - Valerio Piacenti
- Royal College of Surgeons in Ireland, Department of Pharmaceutical and Medicinal Chemistry, Dublin, Ireland
| | - Marilisa Leone
- Institute of Biostructures and Bioimaging, National Research Council, Naples, Italy
| | - Mauro F. A. Adamo
- Royal College of Surgeons in Ireland, Department of Pharmaceutical and Medicinal Chemistry, Dublin, Ireland
| | - Michele Saviano
- Institute of Crystallography, National Research Council, Department of Chemical Sciences and Materials Technologies, Bari, Italy
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10
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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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11
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Antibacterial Peptide Nucleic Acids-Facts and Perspectives. Molecules 2020; 25:molecules25030559. [PMID: 32012929 PMCID: PMC7038079 DOI: 10.3390/molecules25030559] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Revised: 01/20/2020] [Accepted: 01/22/2020] [Indexed: 12/13/2022] Open
Abstract
Antibiotic resistance is an escalating, worldwide problem. Due to excessive use of antibiotics, multidrug-resistant bacteria have become a serious threat and a major global healthcare problem of the 21st century. This fact creates an urgent need for new and effective antimicrobials. The common strategies for antibiotic discovery are based on either modifying existing antibiotics or screening compound libraries, but these strategies have not been successful in recent decades. An alternative approach could be to use gene-specific oligonucleotides, such as peptide nucleic acid (PNA) oligomers, that can specifically target any single pathogen. This approach broadens the range of potential targets to any gene with a known sequence in any bacterium, and could significantly reduce the time required to discover new antimicrobials or their redesign, if resistance arises. We review the potential of PNA as an antibacterial molecule. First, we describe the physicochemical properties of PNA and modifications of the PNA backbone and nucleobases. Second, we review the carriers used to transport PNA to bacterial cells. Furthermore, we discuss the PNA targets in antibacterial studies focusing on antisense PNA targeting bacterial mRNA and rRNA.
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12
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Indumathi K, Abiram A, Praveena G. Effect of peptidic backbone on the nucleic acid dimeric strands. Mol Phys 2020. [DOI: 10.1080/00268976.2019.1584682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- K. Indumathi
- Department of Physics, PSGR Krishnammal College for Women, Coimbatore, India
| | - A. Abiram
- Department of Physics, Karunya Institute of Technology and Sciences, Coimbatore, India
| | - G. Praveena
- Department of Physics, PSGR Krishnammal College for Women, Coimbatore, India
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13
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Jasiński M, Miszkiewicz J, Feig M, Trylska J. Thermal Stability of Peptide Nucleic Acid Complexes. J Phys Chem B 2019; 123:8168-8177. [PMID: 31491077 DOI: 10.1021/acs.jpcb.9b05168] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Peptide nucleic acid (PNA) is a neutral nucleic acid analogue that base pairs with itself and natural nucleic acids. PNA-nucleic acid complexes are more thermally stable than the corresponding complexes of natural nucleic acids. In addition, PNA is biostable and thus used in many antisense and antigene applications to block functional RNA or DNA via sequence-specific interactions. We have recently developed force field parameters for molecular dynamics (MD) simulations of PNA and PNA-involving duplexes with natural nucleic acids. In this work, we provide the first application of this force field to biologically relevant PNA sequences and their complexes with RNA. We investigated thermal stabilities of short PNA-PNA, PNA-RNA, and RNA-RNA duplexes using UV-monitored thermal denaturation experiments and MD simulations at ambient and elevated temperatures. The simulations show a two-state melting transition and reproduce the thermal stability from melting experiments, with PNA-PNA being the most and RNA-RNA the least stable. The PNA-PNA duplex also displays the highest activation energy for melting. The atomistic details of unfolding of PNA duplexes suggest that all PNA-PNA bases melt concomitantly, whereas the RNA-RNA and PNA-RNA are destabilized from the termini toward the central part of the duplexes.
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Affiliation(s)
| | | | - Michael Feig
- Department of Biochemistry and Molecular Biology , Michigan State University , 603 Wilson Road , East Lansing , Michigan 48824 , United States
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14
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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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15
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Peptide Nucleic Acids as miRNA Target Protectors for the Treatment of Cystic Fibrosis. Molecules 2017; 22:molecules22071144. [PMID: 28698463 PMCID: PMC6152032 DOI: 10.3390/molecules22071144] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 07/03/2017] [Accepted: 07/04/2017] [Indexed: 12/12/2022] Open
Abstract
Cystic Fibrosis (CF) is one of the most common life shortening conditions in Caucasians. CF is caused by mutations in the CF Transmembrane Conductance Regulator (CFTR) gene which result in reduced or altered CFTR functionality. Several microRNAs (miRNAs) downregulate the expression of CFTR, thus causing or exacerbating the symptoms of CF. In this context, the design of anti-miRNA agents represents a valid functional tool, but its translation to the clinic might lead to unpredictable side effects because of the interference with the expression of other genes regulated by the same miRNAs. Herein, for the first time, is proposed the use of peptide nucleic acids (PNAs) to protect specific sequences in the 3’UTR (untranslated region) of the CFTR messenger RNA (mRNA) by action of miRNAs. Two PNAs (7 and 13 bases long) carrying the tetrapeptide Gly-SerP-SerP-Gly at their C-end, fully complementary to the 3’UTR sequence recognized by miR-509-3p, have been synthesized and the structural features of target PNA/RNA heteroduplexes have been investigated by spectroscopic and molecular dynamics studies. The co-transfection of the pLuc-CFTR-3´UTR vector with different combinations of PNAs, miR-509-3p, and controls in A549 cells demonstrated the ability of the longer PNA to rescue the luciferase activity by up to 70% of the control, thus supporting the use of suitable PNAs to counteract the reduction in the CFTR expression.
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16
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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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17
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Pieńko T, Wierzba AJ, Wojciechowska M, Gryko D, Trylska J. Conformational Dynamics of Cyanocobalamin and Its Conjugates with Peptide Nucleic Acids. J Phys Chem B 2017; 121:2968-2979. [PMID: 28301169 DOI: 10.1021/acs.jpcb.7b00649] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Vitamin B12 also called cobalamin (Cbl) is an important enzymatic cofactor taken up by mammalian and also by many bacterial cells. Peptide nucleic acid (PNA) is a synthetic DNA analogue that has the ability to bind in a complementary manner to natural nucleic acids. Provided that PNA is efficiently delivered to cells, it could act as a steric blocker of functional DNA or RNA and regulate gene expression at the level of transcription or translation. Recently, Cbl has been examined as a transporter of various molecules to cells. Also, PNA, if covalently linked with Cbl, can be delivered to bacterial cells, but it is crucial to verify that Cbl does not change the desired PNA biological properties. We have analyzed the structure and conformational dynamics of conjugates of Cbl with a PNA monomer and oligomer. We synthesized a cyanocobalamin derivative with a PNA monomer C connected via the triazole linker and determined its NMR spectra. Using microsecond-long molecular dynamics simulations, we examined the internal dynamics of cyanocobalamin-C, its conjugate with a 14-mer PNA, and free PNA. The results suggest that all compounds acquire rather compact structures but the PNA oligomer conformations vary. For the Cbl-C conjugate the cross-peaks from the ROESY spectrum corroborated with the clusters from molecular dynamics trajectories. Within PNA the dominant interaction is stacking but the stacking bases are not necessarily neighboring in the PNA sequence. More bases stack in free PNA than in PNA of the conjugate, but stacking is less stable in free PNA. PNA in the conjugate is slightly more exposed to solvent. Overall, cyanocobalamin attached to a PNA oligomer increases the flexibility of PNA in a way that could be beneficial for its hybridization with natural nucleic acid oligomers.
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Affiliation(s)
- Tomasz Pieńko
- Centre of New Technologies, University of Warsaw , S. Banacha 2c, 02-097 Warsaw, Poland.,Department of Drug Chemistry, Faculty of Pharmacy with the Laboratory Medicine Division, Medical University of Warsaw , S. Banacha 1a, 02-097 Warsaw, Poland
| | - Aleksandra J Wierzba
- Institute of Organic Chemistry, Polish Academy of Sciences , M. Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Monika Wojciechowska
- Centre of New Technologies, University of Warsaw , S. Banacha 2c, 02-097 Warsaw, Poland
| | - Dorota Gryko
- Institute of Organic Chemistry, Polish Academy of Sciences , M. Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Joanna Trylska
- Centre of New Technologies, University of Warsaw , S. Banacha 2c, 02-097 Warsaw, Poland
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18
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Kiliszek A, Banaszak K, Dauter Z, Rypniewski W. The first crystal structures of RNA-PNA duplexes and a PNA-PNA duplex containing mismatches--toward anti-sense therapy against TREDs. Nucleic Acids Res 2015; 44:1937-43. [PMID: 26717983 PMCID: PMC4770230 DOI: 10.1093/nar/gkv1513] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 12/16/2015] [Indexed: 01/02/2023] Open
Abstract
PNA is a promising molecule for antisense therapy of trinucleotide repeat disorders. We present the first crystal structures of RNA–PNA duplexes. They contain CUG repeats, relevant to myotonic dystrophy type I, and CAG repeats associated with poly-glutamine diseases. We also report the first PNA–PNA duplex containing mismatches. A comparison of the PNA homoduplex and the PNA–RNA heteroduplexes reveals PNA's intrinsic structural properties, shedding light on its reported sequence selectivity or intolerance of mismatches when it interacts with nucleic acids. PNA has a much lower helical twist than RNA and the resulting duplex has an intermediate conformation. PNA retains its overall conformation while locally there is much disorder, especially peptide bond flipping. In addition to the Watson–Crick pairing, the structures contain interesting interactions between the RNA's phosphate groups and the Π electrons of the peptide bonds in PNA.
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Affiliation(s)
- Agnieszka Kiliszek
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Katarzyna Banaszak
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Zbigniew Dauter
- Synchrotron Radiation Research Section, MCL, National Cancer Institute, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Wojciech Rypniewski
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
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19
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Anosova I, Kowal EA, Dunn MR, Chaput JC, Van Horn WD, Egli M. The structural diversity of artificial genetic polymers. Nucleic Acids Res 2015; 44:1007-21. [PMID: 26673703 PMCID: PMC4756832 DOI: 10.1093/nar/gkv1472] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2015] [Accepted: 11/30/2015] [Indexed: 11/13/2022] Open
Abstract
Synthetic genetics is a subdiscipline of synthetic biology that aims to develop artificial genetic polymers (also referred to as xeno-nucleic acids or XNAs) that can replicate in vitro and eventually in model cellular organisms. This field of science combines organic chemistry with polymerase engineering to create alternative forms of DNA that can store genetic information and evolve in response to external stimuli. Practitioners of synthetic genetics postulate that XNA could be used to safeguard synthetic biology organisms by storing genetic information in orthogonal chromosomes. XNA polymers are also under active investigation as a source of nuclease resistant affinity reagents (aptamers) and catalysts (xenozymes) with practical applications in disease diagnosis and treatment. In this review, we provide a structural perspective on known antiparallel duplex structures in which at least one strand of the Watson-Crick duplex is composed entirely of XNA. Currently, only a handful of XNA structures have been archived in the Protein Data Bank as compared to the more than 100 000 structures that are now available. Given the growing interest in xenobiology projects, we chose to compare the structural features of XNA polymers and discuss their potential to access new regions of nucleic acid fold space.
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Affiliation(s)
- Irina Anosova
- The Biodesign Institute, Virginia G. Piper Center for Personalized Diagnostics, School of Molecular Sciences, Magnetic Resonance Research Center, Arizona State University, Tempe, AZ 85287-5001, USA
| | - Ewa A Kowal
- Department of Biochemistry, Center for Structural Biology, and Vanderbilt Ingram Cancer Center, Vanderbilt University, School of Medicine, Nashville, TN 37232-0146, USA
| | - Matthew R Dunn
- Department of Pharmaceutical Sciences, University of California-Irvine, Irvine, CA 92697, USA
| | - John C Chaput
- Department of Pharmaceutical Sciences, University of California-Irvine, Irvine, CA 92697, USA
| | - Wade D Van Horn
- The Biodesign Institute, Virginia G. Piper Center for Personalized Diagnostics, School of Molecular Sciences, Magnetic Resonance Research Center, Arizona State University, Tempe, AZ 85287-5001, USA
| | - Martin Egli
- Department of Biochemistry, Center for Structural Biology, and Vanderbilt Ingram Cancer Center, Vanderbilt University, School of Medicine, Nashville, TN 37232-0146, USA
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20
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Accetta A, Petrovic AG, Marchelli R, Berova N, Corradini R. Structural Studies on Porphyrin-PNA Conjugates in Parallel PNA:PNA Duplexes: Effect of Stacking Interactions on Helicity. Chirality 2015; 27:864-74. [PMID: 26412743 DOI: 10.1002/chir.22521] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 08/04/2015] [Accepted: 08/06/2015] [Indexed: 02/01/2023]
Abstract
Parallel PNA:PNA duplexes were synthesized and conjugated with meso-tris(pyridyl)phenylporphyrin carboxylic acid at the N-terminus. The introduction of one porphyrin unit was shown to affect slightly the stability of the PNA:PNA parallel duplex, whereas the presence of two porphyrin units at the same end resulted in a dramatic increase of the melting temperature, accompanied by hysteresis between melting and cooling curves. The circular dichroism (CD) profile of the Soret band and fluorescence quenching strongly support the occurrence of a face-to-face interaction between the two porphyrin units. Introduction of a L-lysine residue at the C-terminal of one strand of the parallel duplex induced a left-handed helical structure in the PNA:PNA duplex if the latter contains only one or no porphyrin moiety. The left-handed helicity was revealed by nucleobase CD profile at 240-280 nm and by the induced-CD observed in the presence of the DiSC2 (5) cyanine dye at ~500-550 nm. Surprisingly, the presence of two porphyrin units led to the disappearance of the nucleobase CD signal and the absence of CD exciton coupling within the Soret band region. In addition, a dramatic decrease of induced CD of DiSC2 (5) was observed. These results are in agreement with a model where the porphyrin-porphyrin interactions cause partial loss of chirality of the PNA:PNA parallel duplex, forcing it to adopt a ladder-like conformation.
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Affiliation(s)
- Alessandro Accetta
- Department of Chemistry, University of Parma, Parma, Italy.,Department of Chemistry, Columbia University, New York, New York, USA
| | - Ana G Petrovic
- Department of Chemistry, Columbia University, New York, New York, USA.,Department of Life Sciences, New York Institute of Technology (NYIT), New York, New York, USA
| | | | - Nina Berova
- Department of Chemistry, Columbia University, New York, New York, USA
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21
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Ovadia R, Lebrun A, Barvik I, Vasseur JJ, Baraguey C, Alvarez K. Synthesis and structural characterization of monomeric and dimeric peptide nucleic acids prepared by using microwave-promoted multicomponent reactions. Org Biomol Chem 2015; 13:11052-71. [PMID: 26394794 DOI: 10.1039/c5ob01604e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A solution phase synthesis of peptide nucleic acid monomers and dimers was developed by using microwave-promoted Ugi multicomponent reactions. A mixture of a functionalized amine, a carboxymethyl nucleobase, paraformaldehyde and an isocyanide as building blocks generates PNA monomers which are then partially deprotected and used in a second Ugi 4CC reaction, leading to PNA dimers. Conformational rotamers were identified by using NMR and MD simulations.
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Affiliation(s)
- Reuben Ovadia
- Laboratoire d'Architecture et Fonction des Macromolécules Biologiques, Université Aix-Marseille UMR CNRS 7257, Equipe "Antiviral Medicinal Chemistry", Parc scientifique de Luminy, 163 av. de Luminy, 13288 Marseille Cedex 9, France.
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22
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Srivastava P, Abou El Asrar R, Knies C, Abramov M, Froeyen M, Rozenski J, Rosemeyer H, Herdewijn P. Achiral, acyclic nucleic acids: synthesis and biophysical studies of a possible prebiotic polymer. Org Biomol Chem 2015; 13:9249-60. [DOI: 10.1039/c5ob00898k] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The search for prebiotic, nucleic acid precursors is, at its best, a speculative undertaking.
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Affiliation(s)
| | | | - C. Knies
- Organic Materials Chemistry and Bioorganic Chemistry
- Institute or Chemistry
- University of Osnabrück
- 49069 Osnabrück
- Germany
| | - M. Abramov
- Medicinal Chemistry
- KU Leuven
- B-3000 Leuven
- Belgium
| | - M. Froeyen
- Medicinal Chemistry
- KU Leuven
- B-3000 Leuven
- Belgium
| | - J. Rozenski
- Medicinal Chemistry
- KU Leuven
- B-3000 Leuven
- Belgium
| | - H. Rosemeyer
- Organic Materials Chemistry and Bioorganic Chemistry
- Institute or Chemistry
- University of Osnabrück
- 49069 Osnabrück
- Germany
| | - P. Herdewijn
- Medicinal Chemistry
- KU Leuven
- B-3000 Leuven
- Belgium
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23
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Autiero I, Saviano M, Langella E. Molecular dynamics simulations of PNA-PNA and PNA-DNA duplexes by the use of new parameters implemented in the GROMACS package: a conformational and dynamics study. Phys Chem Chem Phys 2014; 16:1868-74. [PMID: 24327011 DOI: 10.1039/c3cp54284j] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Peptide Nucleic Acids (PNAs) still represent a growing research area thanks to their potential applications in many fields of science from chemistry and biology to medicine. In these years, structural investigations by means of either experimental or computational techniques have proved to be very useful for the understanding of the structural organization and the binding properties of PNA. In this context, we here report an all-atoms Molecular Dynamics (MD) study of a PNA-PNA duplex and a PNA-DNA hetero-duplex with the well known GROMACS simulation package, by using new force field parameters properly derived for PNA molecules. The good agreement of our results with the crystallographic and NMR data, available for both the systems under investigation, confirms the validity of our approach. Moreover, our simulations reveal new interesting features related to the conformational-dynamic behavior of the studied systems, thus demonstrating the ability of MD simulations to gain insights into the dynamic properties of biologically relevant systems. This force field parametrization represents a good starting point for the implementation of a computational platform, based on the GROMACS package, useful for the rational design of modified PNA molecules with improved conformational features for selective binding toward DNA or RNA.
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Affiliation(s)
- Ida Autiero
- National Research Council, Institute of Biostructures and Bioimaging, 80138 Naples, Italy.
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24
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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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25
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Bachmann SJ, Lin Z, Stafforst T, van Gunsteren WF, Dolenc J. On the Sensitivity of Peptide Nucleic Acid Duplex Formation and Crystal Dissolution to a Variation of Force-Field Parameters. J Chem Theory Comput 2013; 10:391-400. [DOI: 10.1021/ct400652w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Zhixiong Lin
- Laboratory
of Physical Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Thorsten Stafforst
- Laboratory
of Organic Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
| | | | - Jožica Dolenc
- Laboratory
of Physical Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
- Faculty
of Chemistry and Chemical Technology, University of Ljubljana, 1000 Ljubljana, Slovenia
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26
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Sanders JM, Wampole ME, Chen CP, Sethi D, Singh A, Dupradeau FY, Wang F, Gray BD, Thakur ML, Wickstrom E. Effects of hypoxanthine substitution in peptide nucleic acids targeting KRAS2 oncogenic mRNA molecules: theory and experiment. J Phys Chem B 2013; 117:11584-95. [PMID: 23972113 DOI: 10.1021/jp4064966] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Genetic disorders can arise from single base substitutions in a single gene. A single base substitution for wild type guanine in the twelfth codon of KRAS2 mRNA occurs frequently to initiate lung, pancreatic, and colon cancer. We have observed single base mismatch specificity in radioimaging of mutant KRAS2 mRNA in tumors in mice by in vivo hybridization with radiolabeled peptide nucleic acid (PNA) dodecamers. We hypothesized that multimutant specificity could be achieved with a PNA dodecamer incorporating hypoxanthine, which can form Watson-Crick base pairs with adenine, cytosine, thymine, and uracil. Using molecular dynamics simulations and free energy calculations, we show that hypoxanthine substitutions in PNAs are tolerated in KRAS2 RNA:PNA duplexes where wild type guanine is replaced by mutant uracil or adenine in RNA. To validate our predictions, we synthesized PNA dodecamers with hypoxanthine, and then measured the thermal stability of RNA:PNA duplexes. Circular dichroism thermal melting results showed that hypoxanthine-containing PNAs are more stable in duplexes where hypoxanthine-adenine and hypoxanthine-uracil base pairs are formed than single mismatch duplexes or duplexes containing hypoxanthine-guanine opposition.
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Affiliation(s)
- Jeffrey M Sanders
- Departments of Biochemistry & Molecular Biology and ∥Radiology, and ⊥Kimmel Cancer Center, Thomas Jefferson University , Philadelphia, Pennsylvania 19107, United States
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27
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Gupta SK, Sur S, Prasad Ojha R, Tandon V. Influence of PNA containing 8-aza-7-deazaadenine on structure stability and binding affinity of PNA·DNA duplex: insights from thermodynamics, counter ion, hydration and molecular dynamics analysis. MOLECULAR BIOSYSTEMS 2013; 9:1958-71. [PMID: 23636232 DOI: 10.1039/c3mb25561a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
This paper describes the synthesis of a novel 8-aza-7-deazapurin-2,6-diamine (DPP)-containing peptide nucleic acid (PNA) monomer and Boc protecting group-based oligomerization of PNA, replacing adenine (A) with DPP monomers in the PNA strand. The PNA oligomers were synthesized against the biologically relevant SV40 promoter region (2494-AATTTTTTTTATTTA-2508) of pEGFP-N3 plasmid. The DPP-PNA·DNA duplex showed enhanced stability as compared to normal duplex (A-PNA·DNA). The electronic distribution of DPP monomer suggested that DPP had better electron donor properties over 2,6-diamino purine. UV melting and thermodynamic analysis revealed that the PNA oligomer containing a diaminopyrazolo(3,4-d)pyrimidine moiety (DPP) stabilized the PNA·DNA hybrids compared to A-PNA·DNA. DPP-PNA·DNA duplex showed higher water activity (Δnw = 38.5) in comparison to A-PNA·DNA duplex (Δnw = 14.5). The 50 ns molecular dynamics simulations of PNA·DNA duplex containing DPP or unmodified nucleobase-A showed average H-bond distances in the DPP-dT base pair of 2.90 Å (OH-N bond) and 2.91 Å (NH-N bond), which were comparably shorter than in the A-dT base pair, in which the average distances were 3.18 Å (OH-N bond) and 2.97 Å (NH-N bond), and there was one additional H-bond in the DPP-dT base pair of around 2.98 Å (O2H-N2 bond), supporting the higher stability of DPP-PNA·DNA. The analysis of molecular dynamics simulation data showed that the system binding free energy increased at a rate of approximately -4.5 kcal mol(-1) per DPP base of the PNA·DNA duplex. In summary, increased thermal stability, stronger hydrogen bonding and more stable conformation in the DPP-PNA·DNA duplex make it a better candidate as antisense/antigene therapeutic agents.
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Affiliation(s)
- Sharad K Gupta
- Dr B. R. Ambedkar Center for Biomedical Research, Delhi, India.
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28
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Berlin YA, Voityuk AA, Ratner MA. DNA base pair stacks with high electric conductance: a systematic structural search. ACS NANO 2012; 6:8216-8225. [PMID: 22901272 DOI: 10.1021/nn3030139] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report a computational search for DNA π-stack structures exhibiting high electric conductance in the hopping regime, based on the INDO/S calculations of electronic coupling and the method of data analysis called k-means clustering. Using homogeneous poly(G)-poly(C) and poly(A)-poly(T) stacks as the simplest structural models, we identify the configurations of neighboring G:C and A:T pairs that allow strong electronic coupling and, therefore, molecular electric conductance much larger than the values reported for the corresponding reference systems in the literature. A computational approach for modeling the impact of thermal fluctuations on the averaged dimer structure was also proposed and applied to the [(G:C),(G:C)] and [(A:T),(A:T)] duplexes. The results of this work may provide guidance for the construction of DNA devices and DNA-based elements of nanoscale molecular circuits. Several factors that cause changes of step parameters favorable to the formation of the predicted stack conformation with high electric conductance of DNA molecules are also discussed; favorable geometries may enhance the conductivity by factors as large as 15.
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Affiliation(s)
- Yuri A Berlin
- Department of Chemistry, Northwestern University, 1145 Sheridan Road, Evanston, Illinois 60208-3113, United States
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29
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Wierzbinski E, de Leon A, Yin X, Balaeff A, Davis KL, Reppireddy S, Venkatramani R, Keinan S, Ly DH, Madrid M, Beratan DN, Achim C, Waldeck DH. Effect of Backbone Flexibility on Charge Transfer Rates in Peptide Nucleic Acid Duplexes. J Am Chem Soc 2012; 134:9335-42. [DOI: 10.1021/ja301677z] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Emil Wierzbinski
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania
15260, United States
| | - Arnie de Leon
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania
15213, United States
| | - Xing Yin
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania
15260, United States
| | - Alexander Balaeff
- Department
of Chemistry, Duke University, Durham,
North Carolina 27708, United
States
| | - Kathryn L. Davis
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania
15260, United States
| | - Srinivas Reppireddy
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania
15213, United States
| | - Ravindra Venkatramani
- Department
of Chemistry, Duke University, Durham,
North Carolina 27708, United
States
| | - Shahar Keinan
- Department
of Chemistry, Duke University, Durham,
North Carolina 27708, United
States
| | - Danith H. Ly
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania
15213, United States
| | - Marcela Madrid
- Pittsburgh Supercomputing Center, Pittsburgh, Pennsylvania 15213, United States
| | - David N. Beratan
- Departments of Chemistry, Biochemistry,
and Physics, Duke University, Durham, North
Carolina 27708, United States
| | - Catalina Achim
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania
15213, United States
| | - David H. Waldeck
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania
15260, United States
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Features of "All LNA" Duplexes Showing a New Type of Nucleic Acid Geometry. J Nucleic Acids 2012; 2012:156035. [PMID: 22666550 PMCID: PMC3361345 DOI: 10.1155/2012/156035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 03/01/2012] [Indexed: 12/18/2022] Open
Abstract
"Locked nucleic acids" (LNAs) belong to the backbone-modified nucleic acid family. The 2'-O,4'-C-methylene-β-D-ribofuranose nucleotides are used for single or multiple substitutions in RNA molecules and thereby introduce enhanced bio- and thermostability. This renders LNAs powerful tools for diagnostic and therapeutic applications. RNA molecules maintain the overall canonical A-type conformation upon substitution of single or multiple residues/nucleotides by LNA monomers. The structures of "all" LNA homoduplexes, however, exhibit significant differences in their overall geometry, in particular a decreased twist, roll and propeller twist. This results in a widening of the major groove, a decrease in helical winding, and an enlarged helical pitch. Therefore, the LNA duplex structure can no longer be described as a canonical A-type RNA geometry but can rather be brought into proximity to other backbone-modified nucleic acids, like glycol nucleic acids or peptide nucleic acids. LNA-modified nucleic acids provide thus structural and functional features that may be successfully exploited for future application in biotechnology and drug discovery.
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31
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Siriwong K, Voityuk AA. Electron transfer in DNA. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2012. [DOI: 10.1002/wcms.1102] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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32
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Properties of an LNA-modified ricin RNA aptamer. Biochem Biophys Res Commun 2012; 419:60-5. [PMID: 22326915 DOI: 10.1016/j.bbrc.2012.01.127] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Accepted: 01/26/2012] [Indexed: 11/21/2022]
Abstract
'Locked nucleic acids' (LNAs) are sugar modified nucleic acids containing the 2'-O-4'C-methylene-β-D-ribofuranoses. The substitution of RNAs with LNAs leads to an enhanced thermostability. Aptamers are nucleic acids, which are selected for specific target binding from a large library pool by the 'SELEX' method. Introduction of modified nucleic acids into aptamers can improve their stability. The stem region of a ricin A chain RNA aptamer was substituted by locked nucleic acids. Different constructs of the LNA-substituted aptamers were examined for their thermostability, binding activity, folding and RNase sensitivity as compared to the natural RNA counterpart. The LNA-modified aptamers were active in target binding, while the loop regions and the adjacent stem nucleotides remained unsubstituted. The thermostability and RNase resistance of LNA substituted aptamers were enhanced as compared to the native RNA aptamer. This study supports the approach to substitute the aptamer stem region by LNAs and to leave the loop region unmodified, which is responsible for ligand binding. Thus, LNAs possess an encouraging potential for the development of new stabilized nucleic acids and will promote future diagnostic and therapeutic applications.
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33
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Bezer S, Rapireddy S, Skorik YA, Ly DH, Achim C. Coordination-driven inversion of handedness in ligand-modified PNA. Inorg Chem 2011; 50:11929-37. [PMID: 22059624 DOI: 10.1021/ic200855p] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peptide nucleic acid (PNA) is a synthetic analogue of DNA, which has the same nucleobases as DNA but typically has a backbone based on aminoethyl glycine (Aeg). PNA forms duplexes by Watson Crick hybridization. The Aeg-based PNA duplexes adopt a chiral helical structure but do not have a preferred handedness because they do not contain a chiral center. An L-lysine situated at the C-end of one or both strands of a PNA duplex causes the duplex to preferably adopt a left-handed structure. We have introduced into the PNA duplexes both a C-terminal L-lysine and one or two PNA monomers that have a γ-(S)-methyl-aminoethyl glycine backbone, which is known to induce a preference for a right-handed structure. Indeed, we found that in these duplexes the γ-methyl monomer exerts the dominant chiral induction effect causing the duplexes to adopt a right-handed structure. The chiral PNA monomer had a 2,2':6',2''-terpyridine (Tpy) ligand instead of a nucleobase and PNA duplexes that contained one or two Tpys formed [Cu(Tpy)(2)](2+) complexes in the presence of Cu(2+). The CD spectroscopy studies showed that these metal-coordinated duplexes were right-handed due to the chiral induction effect exerted by the S-Tpy PNA monomer(s) except for the cases when the [Cu(Tpy)(2)](2+) complex was formed with Tpy ligands from two different PNA duplexes. In the latter case, the metal complex bridged the two PNA duplexes and the duplexes were left-handed. The results of this study show that the preferred handedness of a ligand-modified PNA can be switched as a consequence of metal coordination to the ligand. This finding could be used as a tool in the design of functional nucleic-acid based nanostructures.
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Affiliation(s)
- Silvia Bezer
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213-3890, USA
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34
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Johnson AT, Schlegel MK, Meggers E, Essen LO, Wiest O. On the structure and dynamics of duplex GNA. J Org Chem 2011; 76:7964-74. [PMID: 21838272 DOI: 10.1021/jo201469b] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Glycol nucleic acid (GNA), with a nucleotide backbone comprising of just three carbons and the stereocenter derived from propylene glycol (1,2-propanediol), is a structural analog of nucleic acids with intriguing biophysical properties, such as formation of highly stable antiparallel duplexes with high Watson-Crick base pairing fidelity. Previous crystallographic studies of double stranded GNA (dsGNA) indicated two forms of backbone conformations, an elongated M-type (containing metallo-base pairs) and the condensed N-type (containing brominated base pairs). A herein presented new crystal structure of a GNA duplex at 1.8 Å resolution from self-complementary 3'-CTC(Br)UAGAG-2' GNA oligonucleotides reveals an N-type conformation with alternating gauche-anti torsions along its (O3'-C3'-C2'-O2') backbone. To elucidate the conformational state of dsGNA in solution, molecular dynamic simulations over a period of 20 ns were performed with the now available repertoire of structural information. Interestingly, dsGNA adopts conformational states in solution intermediate between experimentally observed backbone conformations: simulated dsGNA shows the all-gauche conformation characteristic of M-type GNA with the higher helical twist common to N-type GNA structures. The so far counterintuitive, smaller loss of entropy upon duplex formation as compared to DNA can be traced back to the conformational flexibility inherent to dsGNA but missing in dsDNA. Besides extensive interstrand base stacking and conformational preorganization of single strands, this flexibility contributes to the extraordinary thermal stability of GNA.
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Affiliation(s)
- Andrew T Johnson
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, United States
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35
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Venkatramani R, Keinan S, Balaeff A, Beratan DN. Nucleic Acid Charge Transfer: Black, White and Gray. Coord Chem Rev 2011; 255:635-648. [PMID: 21528017 PMCID: PMC3081592 DOI: 10.1016/j.ccr.2010.12.010] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Theoretical studies of charge transport in deoxyribonucleic acid (DNA) and peptide nucleic acid (PNA) indicate that structure and dynamics modulate the charge transfer rates, and that different members of a structural ensemble support different charge transport mechanisms. Here, we review the influences of nucleobase geometry, electronic structure, solvent environment, and thermal conformational fluctuations on the charge transfer mechanism. We describe an emerging framework for understanding the diversity of charge transport mechanisms seen in nucleic acids.
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Affiliation(s)
| | - Shahar Keinan
- Department of Chemistry, Duke University, Durham, North Carolina 27708
| | - Alexander Balaeff
- Department of Chemistry, Duke University, Durham, North Carolina 27708
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36
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Venkatramani R, Davis KL, Wierzbinski E, Bezer S, Balaeff A, Keinan S, Paul A, Kocsis L, Beratan DN, Achim C, Waldeck DH. Evidence for a near-resonant charge transfer mechanism for double-stranded peptide nucleic acid. J Am Chem Soc 2010; 133:62-72. [PMID: 21141966 DOI: 10.1021/ja107622m] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We present evidence for a near-resonant mechanism of charge transfer in short peptide nucleic acid (PNA) duplexes obtained through electrochemical, STM break junction (STM-BJ), and computational studies. A seven base pair (7-bp) PNA duplex with the sequence (TA)(3)-(XY)-(TA)(3) was studied, in which XY is a complementary nucleobase pair. The experiments showed that the heterogeneous charge transfer rate constant (k(0)) and the single-molecule conductance (σ) correlate with the oxidation potential of the purine base in the XY base pair. The electrochemical measurements showed that the enhancement of k(0) is independent, within experimental error, of which of the two PNA strands contains the purine base of the XY base pair. 7-bp PNA duplexes with one or two GC base pairs had similar measured k(0) and conductance values. While a simple superexchange model, previously used to rationalize charge transfer in single stranded PNA (Paul et al. J. Am. Chem. Soc. 2009, 131, 6498-6507), describes some of the experimental observations, the model does not explain the absence of an enhancement in the experimental k(0) and σ upon increasing the G content in the duplexes from one to two. Moreover, the superexchange model is not consistent with other studies (Paul et al. J. Phys. Chem. B 2010, 114, 14140), that showed a hopping charge transport mechanism is likely important for PNA duplexes longer than seven base pairs. A quantitative computational analysis shows that a near-resonant charge transfer regime, wherein a mix of superexchange and hopping mechanisms are expected to coexist, can rationalize all of the experimental results.
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37
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Abstract
Since the structure of DNA was elucidated more than 50 years ago, Watson-Crick base pairing has been widely speculated to be the likely mode of both information storage and transfer in the earliest genetic polymers. The discovery of catalytic RNA molecules subsequently provided support for the hypothesis that RNA was perhaps even the first polymer of life. However, the de novo synthesis of RNA using only plausible prebiotic chemistry has proven difficult, to say the least. Experimental investigations, made possible by the application of synthetic and physical organic chemistry, have now provided evidence that the nucleobases (A, G, C, and T/U), the trifunctional moiety ([deoxy]ribose), and the linkage chemistry (phosphate esters) of contemporary nucleic acids may be optimally suited for their present roles-a situation that suggests refinement by evolution. Here, we consider studies of variations in these three distinct components of nucleic acids with regard to the question: Is RNA, as is generally acknowledged of DNA, the product of evolution? If so, what chemical and structural features might have been more likely and advantageous for a proto-RNA?
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Affiliation(s)
- Aaron E Engelhart
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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38
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Yeh JI, Shivachev B, Rapireddy S, Crawford MJ, Gil RR, Du S, Madrid M, Ly DH. Crystal structure of chiral gammaPNA with complementary DNA strand: insights into the stability and specificity of recognition and conformational preorganization. J Am Chem Soc 2010; 132:10717-27. [PMID: 20681704 DOI: 10.1021/ja907225d] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have determined the structure of a PNA-DNA duplex to 1.7 A resolution by multiple-wavelength anomalous diffraction phasing method on a zinc derivative. This structure represents the first high-resolution 3D view of a hybrid duplex containing a contiguous chiral PNA strand with complete gamma-backbone modification ("gammaPNA"). Unlike the achiral counterpart, which adopts a random-fold, this particular gammaPNA is already preorganized into a right-handed helix as a single strand. The new structure illustrates the unique characteristics of this modified PNA, possessing conformational flexibility while maintaining sufficient structural integrity to ultimately adopt the preferred P-helical conformation upon hybridization with DNA. The unusual structural adaptability found in the gammaPNA strand is crucial for enabling the accommodation of backbone modifications while constraining conformational states. In conjunction with NMR analysis characterizing the structures and substructures of the individual building blocks, these results provide unprecedented insights into how this new class of chiral gammaPNA is preorganized and stabilized, before and after hybridization with a cDNA strand. Such knowledge is crucial for the future design and development of PNA for applications in biology, biotechnology, and medicine.
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Affiliation(s)
- Joanne I Yeh
- Department of Structural Biology, University of Pittsburgh Medical School 1036 BST3, 3501 Fifth Avenue, Pittsburgh, Pennsylvania 15260, USA.
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39
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Yeh JI, Pohl E, Truan D, He W, Sheldrick GM, Du S, Achim C. The crystal structure of non-modified and bipyridine-modified PNA duplexes. Chemistry 2010; 16:11867-75. [PMID: 20859960 PMCID: PMC3194003 DOI: 10.1002/chem.201000392] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Peptide nucleic acid (PNA) is a synthetic analogue of DNA that commonly has an N-aminoethyl glycine backbone. The crystal structures of two PNA duplexes, one containing eight standard nucleobase pairs (GGCATGCC)(2), and the other containing the same nucleobase pairs and a central pair of bipyridine ligands, have been solved with a resolution of 1.22 and 1.10 Å, respectively. The non-modified PNA duplex adopts a P-type helical structure similar to that of previously characterized PNAs. The atomic-level resolution of the structures allowed us to observe for the first time specific modes of interaction between the terminal lysines of the PNA and the backbone and the nucleobases situated in the vicinity of the lysines, which are considered an important factor in the induction of a preferred handedness in PNA duplexes. Our results support the notion that whereas PNA typically adopts a P-type helical structure, its flexibility is relatively high. For example, the base-pair rise in the bipyridine-containing PNA is the largest measured to date in a PNA homoduplex. The two bipyridines bulge out of the duplex and are aligned parallel to the major groove of the PNA. In addition, two bipyridines from adjacent PNA duplexes form a π-stacked pair that relates the duplexes within the crystal. The bulging out of the bipyridines causes bending of the PNA duplex, which is in contrast to the structure previously reported for biphenyl-modified DNA duplexes in solution, where the biphenyls are π stacked with adjacent nucleobase pairs and adopt an intrahelical geometry. This difference shows that relatively small perturbations can significantly impact the relative position of nucleobase analogues in nucleic acid duplexes.
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Affiliation(s)
- Joanne I. Yeh
- Department of Structural Biology University of Pittsburgh Medical School Pittsburgh, PA 15260 (USA)
| | - Ehmke Pohl
- Department of Chemistry and School of Biological and Biomedical Sciences Durham University South Road, Durham DH1 3LE (UK)
| | - Daphne Truan
- Swiss Light Source Paul Scherrer Institute, CH-52323 Villigen, PSI (Switzerland)
| | - Wei He
- Department of Chemistry Carnegie Mellon University 4400 5 Ave., Pittsburgh, PA 15213 (USA)
| | - George M. Sheldrick
- Institut of Inorganic Chemistry University of GöttingenTammanstr. 4, 37077 Göttingen (Germany)
| | - Shoucheng Du
- Department of Structural Biology University of Pittsburgh Medical School Pittsburgh, PA 15260 (USA)
| | - Catalina Achim
- Department of Chemistry Carnegie Mellon University 4400 5 Ave., Pittsburgh, PA 15213 (USA)
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40
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He W, Crawford MJ, Rapireddy S, Madrid M, Gil RR, Ly DH, Achim C. The structure of a gamma-modified peptide nucleic acid duplex. MOLECULAR BIOSYSTEMS 2010; 6:1619-29. [PMID: 20386807 DOI: 10.1039/c002254c] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This paper presents the results of an NMR spectroscopy and distance-restrained molecular dynamics (MD) study of a gamma-methylated, palindromic, 8-base pair peptide nucleic acid (gamma-PNA) duplex. The goal of this study was to examine the impact of the gamma-backbone modification on the structure of the PNA duplex. The 2D NMR information involving the backbone methyl group, especially the NOEs between the methyl protons and those of the amide and methylene groups of the backbone, led to distance restraints useful in the elucidation of the structure of the backbone of gamma-PNA. Integration of the NOE peaks resulted in 138 inter-proton distance restraints, which were used in ten independent simulated annealing followed by 2 ns restrained MD runs. These simulations led to the conclusion that the gamma-PNA duplex adopts a general P-form helical structure similar to that observed for non-modified PNA but with a smaller base pair rise, which is an A-like helical feature, and a slight helical bending towards the major groove (PDB ID ). These properties of the gamma-PNA duplex may be induced by the gamma-methyl group. A similar effect of the methyl group was revealed by a previous NMR study of single stranded gamma-PNA [A. Dragulescu-Andrasi, S. Rapireddy, B. M. Frezza, C. Gayathri, R. R. Gil and D. H. Ly, J. Am. Chem. Soc., 2006, 128, 10258-10267]. It appears that the steric constraint exerted by the gamma-methyl on the backbone orientation is relatively independent of the base pairing and stacking and thus is likely to manifest when other substituents are introduced at the gamma-position of the PNA.
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Affiliation(s)
- Wei He
- Department of Chemistry, Carnegie Mellon University, 4400 5th Avenue, Pittsburgh, PA 15213, USA
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41
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Totsingan F, Jain V, Bracken WC, Faccini A, Tedeschi T, Marchelli R, Corradini R, Kallenbach NR, Green MM. Conformational Heterogeneity in PNA:PNA Duplexes. Macromolecules 2010. [DOI: 10.1021/ma902797f] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Filbert Totsingan
- Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003
- Herman F. Mark Polymer Research Institute, Polytechnic Institute of New York University, 6 MetroTech Center, Brooklyn, New York 11201
- Dipartimento di Chimica Organica ed Industriale, Università di Parma, Via G.P. Usberti 17/A, 43100 Parma, Italy
| | - Vipul Jain
- Herman F. Mark Polymer Research Institute, Polytechnic Institute of New York University, 6 MetroTech Center, Brooklyn, New York 11201
| | - W. Clay Bracken
- Department of Biochemistry, Weill Medical College of Cornell University, 1300 York Avenue, New York, New York 10021
| | - Andrea Faccini
- Dipartimento di Chimica Organica ed Industriale, Università di Parma, Via G.P. Usberti 17/A, 43100 Parma, Italy
| | - Tullia Tedeschi
- Dipartimento di Chimica Organica ed Industriale, Università di Parma, Via G.P. Usberti 17/A, 43100 Parma, Italy
| | - Rosangela Marchelli
- Dipartimento di Chimica Organica ed Industriale, Università di Parma, Via G.P. Usberti 17/A, 43100 Parma, Italy
| | - Roberto Corradini
- Dipartimento di Chimica Organica ed Industriale, Università di Parma, Via G.P. Usberti 17/A, 43100 Parma, Italy
| | - Neville R. Kallenbach
- Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003
| | - Mark M. Green
- Herman F. Mark Polymer Research Institute, Polytechnic Institute of New York University, 6 MetroTech Center, Brooklyn, New York 11201
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42
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Voityuk AA. Can charge transfer in DNA significantly be modulated by varying the pi stack conformation? J Phys Chem B 2010; 113:14365-8. [PMID: 19795825 DOI: 10.1021/jp908603w] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
DNA is an ideal target for single-molecule manipulations. The conformation of stacked basepairs in DNA depends sensitively on various factors such as temperature, the kind of solvent and counterions, changes in the backbone, applied forces, etc. This raises the question of whether the rate of charge transfer (CT) through the stack can be considerably enhanced by tuning of "observed" DNA conformations. Using a stochastic approach to account for the effects of thermal fluctuations, we study how the efficiency of CT in poly(dA)-poly(dT) and poly(dG)-poly(dC) sequences will change by variation of the pi stack structure. The CT process is shown to be not very sensitive to the torsional angle (twist) while affected more strongly by altering translation modes (shift and slide). We conclude that the design of basepair stacks with significantly improved electrical conductivity, as compared to poly(dG)-poly(dC), appears to be quite elusive. Specific changes of the pi stack structure can increase the efficiency of CT by a factor of approximately 3 (e.g., in systems with negative shift); much stronger effects can hardly be expected. This result, formally derived for molecular ensembles, should also be applicable for single-molecule systems because of the strong effects of dynamical disordering.
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43
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Butchosa C, Simon S, Voityuk AA. Electron transfer from aromatic amino acids to guanine and adenine radical cations in π stacked and T-shaped complexes. Org Biomol Chem 2010; 8:1870-5. [DOI: 10.1039/b927134a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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44
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Paul A, Watson RM, Wierzbinski E, Davis KL, Sha A, Achim C, Waldeck DH. Distance dependence of the charge transfer rate for peptide nucleic acid monolayers. J Phys Chem B 2009; 114:14140-8. [PMID: 19691305 DOI: 10.1021/jp906910h] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Charge transfer studies have been performed for self-assembled monolayers of single-stranded and double-stranded peptide nucleic acids (PNAs) having a C-terminus cysteine and an N-terminus ferrocene group as a redox reporter. The decay of the charge transfer rate with distance was strong for short single-stranded PNA molecules and weak for long single-stranded and double-stranded PNAs. Possible mechanisms for this "softening" of the distance dependence are discussed. The nature of the mechanism change can be explained by a transition of the charge transport mechanism from superexchange-mediated tunneling for short PNAs to a "hopping" mechanism for long PNAs.
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Affiliation(s)
- Amit Paul
- Department of Chemistry, University of Pittsburgh, Pennsylvania 15260, USA
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45
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Paul A, Bezer S, Venkatramani R, Kocsis L, Wierzbinski E, Balaeff A, Keinan S, Beratan DN, Achim C, Waldeck DH. Role of nucleobase energetics and nucleobase interactions in single-stranded peptide nucleic acid charge transfer. J Am Chem Soc 2009; 131:6498-507. [PMID: 19382798 DOI: 10.1021/ja9000163] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Self-assembled monolayers of single-stranded (ss) peptide nucleic acids (PNAs) containing seven nucleotides (TTTXTTT), a C-terminus cysteine, and an N-terminus ferrocene redox group were formed on gold electrodes. The PNA monomer group (X) was selected to be either cytosine (C), thymine (T), adenine (A), guanine (G), or a methyl group (Bk). The charge transfer rate through the oligonucleotides was found to correlate with the oxidation potential of X. Kinetic measurements and computational studies of the ss-PNA fragments show that a nucleobase mediated charge transport mechanism in the deep tunneling superexchange regime can explain the observed dependence of the kinetics of charge transfer on the PNA sequence. Theoretical analysis suggests that the charge transport is dominantly hole-mediated and takes place through the filled bridge orbitals. The strongest contribution to conductance comes from the highest filled orbitals (HOMO, HOMO-1, and HOMO-2) of individual bases, with a rapid drop off in contributions from lower lying filled orbitals. Our studies further suggest that the linear correlation observed between the experimental charge transfer rates and the oxidation potential of base X arises from weak average interbase couplings and similar stacking geometries for the four TTTXTTT systems.
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Affiliation(s)
- Amit Paul
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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