1
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Abdullin D, Rauh Corro P, Hett T, Schiemann O. PDSFit: PDS data analysis in the presence of orientation selectivity, g-anisotropy, and exchange coupling. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2024; 62:37-60. [PMID: 38130168 DOI: 10.1002/mrc.5415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 10/24/2023] [Accepted: 11/01/2023] [Indexed: 12/23/2023]
Abstract
Pulsed dipolar electron paramagnetic resonance spectroscopy (PDS), encompassing techniques such as pulsed electron-electron double resonance (PELDOR or DEER) and relaxation-induced dipolar modulation enhancement (RIDME), is a valuable method in structural biology and materials science for obtaining nanometer-scale distance distributions between electron spin centers. An important aspect of PDS is the extraction of distance distributions from the measured time traces. Most software used for this PDS data analysis relies on simplifying assumptions, such as assuming isotropic g-factors of ~2 and neglecting orientation selectivity and exchange coupling. Here, the program PDSFit is introduced, which enables the analysis of PELDOR and RIDME time traces with or without orientation selectivity. It can be applied to spin systems consisting of up to two spin centers with anisotropic g-factors and to spin systems with exchange coupling. It employs a model-based fitting of the time traces using parametrized distance and angular distributions, and parametrized PDS background functions. The fitting procedure is followed by an error analysis for the optimized parameters of the distributions and backgrounds. Using five different experimental data sets published previously, the performance of PDSFit is tested and found to provide reliable solutions.
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Affiliation(s)
- Dinar Abdullin
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn, Germany
| | - Pablo Rauh Corro
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn, Germany
| | - Tobias Hett
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn, Germany
| | - Olav Schiemann
- Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn, Germany
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2
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Fábregas-Ibáñez L, Mertens V, Ritsch I, von Hagens T, Stoll S, Jeschke G. Dipolar pathways in multi-spin and multi-dimensional dipolar EPR spectroscopy. Phys Chem Chem Phys 2022; 24:22645-22660. [PMID: 36106486 PMCID: PMC9516884 DOI: 10.1039/d2cp03048a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 09/07/2022] [Indexed: 11/24/2022]
Abstract
Dipolar electron paramagnetic resonance (EPR) experiments, such as double electron-electron resonance (DEER), measure distributions of nanometer-scale distances between unpaired electrons, which provide valuable information for structural characterization of proteins and other macromolecular systems. We present an extension to our previously published general model based on dipolar pathways valid for multi-dimensional dipolar EPR experiments with more than two spin-1/2 labels. We examine the 4-pulse DEER and TRIER experiments in terms of dipolar pathways and show experimental results confirming the theoretical predictions. This extension to the dipolar pathways model allows the analysis of previously challenging datasets and the extraction of multivariate distance distributions.
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Affiliation(s)
- Luis Fábregas-Ibáñez
- ETH Zurich, Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, Zurich, Switzerland
| | - Valerie Mertens
- ETH Zurich, Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, Zurich, Switzerland
| | - Irina Ritsch
- ETH Zurich, Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, Zurich, Switzerland
| | - Tona von Hagens
- ETH Zurich, Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, Zurich, Switzerland
| | - Stefan Stoll
- Department of Chemistry, University of Washington, Seattle, WA 98195, Washington, USA
| | - Gunnar Jeschke
- ETH Zurich, Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, Zurich, Switzerland
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3
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Peter MF, Gebhardt C, Mächtel R, Muñoz GGM, Glaenzer J, Narducci A, Thomas GH, Cordes T, Hagelueken G. Cross-validation of distance measurements in proteins by PELDOR/DEER and single-molecule FRET. Nat Commun 2022; 13:4396. [PMID: 35906222 PMCID: PMC9338047 DOI: 10.1038/s41467-022-31945-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 07/11/2022] [Indexed: 11/09/2022] Open
Abstract
Pulsed electron-electron double resonance spectroscopy (PELDOR/DEER) and single-molecule Förster resonance energy transfer spectroscopy (smFRET) are frequently used to determine conformational changes, structural heterogeneity, and inter probe distances in biological macromolecules. They provide qualitative information that facilitates mechanistic understanding of biochemical processes and quantitative data for structural modelling. To provide a comprehensive comparison of the accuracy of PELDOR/DEER and smFRET, we use a library of double cysteine variants of four proteins that undergo large-scale conformational changes upon ligand binding. With either method, we use established standard experimental protocols and data analysis routines to determine inter-probe distances in the presence and absence of ligands. The results are compared to distance predictions from structural models. Despite an overall satisfying and similar distance accuracy, some inconsistencies are identified, which we attribute to the use of cryoprotectants for PELDOR/DEER and label-protein interactions for smFRET. This large-scale cross-validation of PELDOR/DEER and smFRET highlights the strengths, weaknesses, and synergies of these two important and complementary tools in integrative structural biology.
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Affiliation(s)
- Martin F Peter
- Institute of Structural Biology, University of Bonn, Bonn, Germany
| | - Christian Gebhardt
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Rebecca Mächtel
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Gabriel G Moya Muñoz
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Janin Glaenzer
- Institute of Structural Biology, University of Bonn, Bonn, Germany
| | - Alessandra Narducci
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Gavin H Thomas
- Department of Biology (Area 10), University of York, York, UK
| | - Thorben Cordes
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany.
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4
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Fábregas-Ibáñez L, Tessmer MH, Jeschke G, Stoll S. Dipolar pathways in dipolar EPR spectroscopy. Phys Chem Chem Phys 2022; 24:2504-2520. [PMID: 35023519 PMCID: PMC8920025 DOI: 10.1039/d1cp03305k] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Dipolar electron paramagnetic resonance (EPR) experiments such as double electron-electron resonance (DEER) measure distributions of nanometer-scale distances between unpaired electrons, which provide valuable information for structural characterization of proteins and other macromolecular systems. To determine these distributions from the experimental signal, it is critical to employ an accurate model of the signal. For dilute samples of doubly spin-labeled molecules, the signal is a product of an intramolecular and an intermolecular contribution. We present a general model based on dipolar pathways valid for dipolar EPR experiments with spin-1/2 labels. Our results show that the intramolecular contribution consists of a sum and the intermolecular contribution consists of a product over individual dipolar pathway contributions. We examine several commonly used dipolar EPR experiments in terms of dipolar pathways and show experimental results confirming the theoretical predictions. This multi-pathway model makes it possible to analyze a wide range of dipolar EPR experiments within a single theoretical framework.
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Affiliation(s)
- Luis Fábregas-Ibáñez
- ETH Zurich, Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Maxx H Tessmer
- University of Washington, Department of Chemistry, Seattle, WA 98195, USA.
| | - Gunnar Jeschke
- ETH Zurich, Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Stefan Stoll
- University of Washington, Department of Chemistry, Seattle, WA 98195, USA.
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5
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Schiemann O, Heubach CA, Abdullin D, Ackermann K, Azarkh M, Bagryanskaya EG, Drescher M, Endeward B, Freed JH, Galazzo L, Goldfarb D, Hett T, Esteban Hofer L, Fábregas Ibáñez L, Hustedt EJ, Kucher S, Kuprov I, Lovett JE, Meyer A, Ruthstein S, Saxena S, Stoll S, Timmel CR, Di Valentin M, Mchaourab HS, Prisner TF, Bode BE, Bordignon E, Bennati M, Jeschke G. Benchmark Test and Guidelines for DEER/PELDOR Experiments on Nitroxide-Labeled Biomolecules. J Am Chem Soc 2021; 143:17875-17890. [PMID: 34664948 PMCID: PMC11253894 DOI: 10.1021/jacs.1c07371] [Citation(s) in RCA: 107] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Distance distribution information obtained by pulsed dipolar EPR spectroscopy provides an important contribution to many studies in structural biology. Increasingly, such information is used in integrative structural modeling, where it delivers unique restraints on the width of conformational ensembles. In order to ensure reliability of the structural models and of biological conclusions, we herein define quality standards for sample preparation and characterization, for measurements of distributed dipole-dipole couplings between paramagnetic labels, for conversion of the primary time-domain data into distance distributions, for interpreting these distributions, and for reporting results. These guidelines are substantiated by a multi-laboratory benchmark study and by analysis of data sets with known distance distribution ground truth. The study and the guidelines focus on proteins labeled with nitroxides and on double electron-electron resonance (DEER aka PELDOR) measurements and provide suggestions on how to proceed analogously in other cases.
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Affiliation(s)
- Olav Schiemann
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstraße 12, 53115 Bonn, Germany
| | - Caspar A Heubach
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstraße 12, 53115 Bonn, Germany
| | - Dinar Abdullin
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstraße 12, 53115 Bonn, Germany
| | - Katrin Ackermann
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex, and Centre of Magnetic Resonance, University of St Andrews North Haugh, St Andrews KY16 9ST, U.K
| | - Mykhailo Azarkh
- Department of Chemistry and Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Elena G Bagryanskaya
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Lavrentieva aven 9, 630090 Novosibirsk, Russia
| | - Malte Drescher
- Department of Chemistry and Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Burkhard Endeward
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University, 60438 Frankfurt am Main, Germany
| | - Jack H Freed
- Department of Chemistry and Chemical Biology, and ACERT, National Biomedical Center for Advanced Electron Spin Resonance Technology, Cornell University, Ithaca, New York 14853-1301, United States
| | - Laura Galazzo
- Faculty of Chemistry and Biochemistry, Ruhr University Bochum, 44801 Bochum, Germany
| | - Daniella Goldfarb
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Tobias Hett
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstraße 12, 53115 Bonn, Germany
| | - Laura Esteban Hofer
- Department of Chemistry and Applied Biosciences, ETH Hönggerberg, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Luis Fábregas Ibáñez
- Department of Chemistry and Applied Biosciences, ETH Hönggerberg, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Eric J Hustedt
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Svetlana Kucher
- Faculty of Chemistry and Biochemistry, Ruhr University Bochum, 44801 Bochum, Germany
| | - Ilya Kuprov
- School of Chemistry, University of Southampton, Highfield Campus, Southampton SO17 1BJ, U.K
| | - Janet Eleanor Lovett
- SUPA School of Physics and Astronomy and BSRC, University of St Andrews, North Haugh, St Andrews KY16 9SS, U.K
| | - Andreas Meyer
- Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Sharon Ruthstein
- Department of Chemistry, Bar Ilan University, Ramat Gan 5290002, Israel
| | - Sunil Saxena
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Stefan Stoll
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Christiane R Timmel
- Department of Chemistry, Centre for Advanced Electron Spin Resonance, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K
| | - Marilena Di Valentin
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy
| | - Hassane S Mchaourab
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Thomas F Prisner
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University, 60438 Frankfurt am Main, Germany
| | - Bela Ernest Bode
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex, and Centre of Magnetic Resonance, University of St Andrews North Haugh, St Andrews KY16 9ST, U.K
| | - Enrica Bordignon
- Faculty of Chemistry and Biochemistry, Ruhr University Bochum, 44801 Bochum, Germany
| | - Marina Bennati
- Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Gunnar Jeschke
- Department of Chemistry and Applied Biosciences, ETH Hönggerberg, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
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6
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Ritsch I, Esteban-Hofer L, Lehmann E, Emmanouilidis L, Yulikov M, Allain FHT, Jeschke G. Characterization of Weak Protein Domain Structure by Spin-Label Distance Distributions. Front Mol Biosci 2021; 8:636599. [PMID: 33912586 PMCID: PMC8072059 DOI: 10.3389/fmolb.2021.636599] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 02/19/2021] [Indexed: 01/04/2023] Open
Abstract
Function of intrinsically disordered proteins may depend on deviation of their conformational ensemble from that of a random coil. Such deviation may be hard to characterize and quantify, if it is weak. We explored the potential of distance distributions between spin labels, as they can be measured by electron paramagnetic resonance techniques, for aiding such characterization. On the example of the intrinsically disordered N-terminal domain 1-267 of fused in sarcoma (FUS) we examined what such distance distributions can and cannot reveal on the random-coil reference state. On the example of the glycine-rich domain 188-320 of heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) we studied whether deviation from a random-coil ensemble can be robustly detected with 19 distance distribution restraints. We discuss limitations imposed by ill-posedness of the conversion of primary data to distance distributions and propose overlap of distance distributions as a fit criterion that can tackle this problem. For testing consistency and size sufficiency of the restraint set, we propose jack-knife resampling. At current desktop computers, our approach is expected to be viable for domains up to 150 residues and for between 10 and 50 distance distribution restraints.
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Affiliation(s)
- Irina Ritsch
- Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland
| | - Laura Esteban-Hofer
- Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland
| | | | | | - Maxim Yulikov
- Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland
| | | | - Gunnar Jeschke
- Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland
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7
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EL Mkami H, Hunter R, Cruickshank P, Taylor M, Lovett J, Feintuch A, Qi M, Godt A, Smith G. High-sensitivity Gd 3+-Gd 3+ EPR distance measurements that eliminate artefacts seen at short distances. MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2020; 1:301-313. [PMID: 37904818 PMCID: PMC10500690 DOI: 10.5194/mr-1-301-2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 11/18/2020] [Indexed: 11/01/2023]
Abstract
Gadolinium complexes are attracting increasing attention as spin labels for EPR dipolar distance measurements in biomolecules and particularly for in-cell measurements. It has been shown that flip-flop transitions within the central transition of the high-spin Gd3 + ion can introduce artefacts in dipolar distance measurements, particularly when measuring distances less than 3 nm. Previous work has shown some reduction of these artefacts through increasing the frequency separation between the two frequencies required for the double electron-electron resonance (DEER) experiment. Here we use a high-power (1 kW), wideband, non-resonant system operating at 94 GHz to evaluate DEER measurement protocols using two stiff Gd(III) rulers, consisting of two b i s -Gd3 + -PyMTA complexes, with separations of 2.1 nm and 6.0 nm, respectively. We show that by avoiding the - 1 2 → 1 2 central transition completely, and placing both the pump and the observer pulses on either side of the central transition, we can now observe apparently artefact-free spectra and narrow distance distributions, even for a Gd-Gd distance of 2.1 nm. Importantly we still maintain excellent signal-to-noise ratio and relatively high modulation depths. These results have implications for in-cell EPR measurements at naturally occurring biomolecule concentrations.
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Affiliation(s)
- Hassane EL Mkami
- SUPA, School of Physics and Astronomy, University of St Andrews, St
Andrews, KY16 9SS, UK
| | - Robert I. Hunter
- SUPA, School of Physics and Astronomy, University of St Andrews, St
Andrews, KY16 9SS, UK
| | - Paul A. S. Cruickshank
- SUPA, School of Physics and Astronomy, University of St Andrews, St
Andrews, KY16 9SS, UK
| | - Michael J. Taylor
- SUPA, School of Physics and Astronomy, University of St Andrews, St
Andrews, KY16 9SS, UK
| | - Janet E. Lovett
- SUPA, School of Physics and Astronomy, University of St Andrews, St
Andrews, KY16 9SS, UK
| | - Akiva Feintuch
- Department of Chemical Physics, Weizmann Institute of Science,
Rehovot, Israel
| | - Mian Qi
- Faculty of Chemistry and Center of Molecular Materials (CM2),
Bielefeld University, Universitätsstraße 25, 33615 Bielefeld,
Germany
| | - Adelheid Godt
- Faculty of Chemistry and Center of Molecular Materials (CM2),
Bielefeld University, Universitätsstraße 25, 33615 Bielefeld,
Germany
| | - Graham M. Smith
- SUPA, School of Physics and Astronomy, University of St Andrews, St
Andrews, KY16 9SS, UK
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8
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Wuebben C, Vicino MF, Mueller M, Schiemann O. Do the P1 and P2 hairpins of the Guanidine-II riboswitch interact? Nucleic Acids Res 2020; 48:10518-10526. [PMID: 32857846 PMCID: PMC7544219 DOI: 10.1093/nar/gkaa703] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 08/08/2020] [Accepted: 08/12/2020] [Indexed: 01/09/2023] Open
Abstract
Riboswitches regulate genes by adopting different structures in responds to metabolite binding. The guanidine-II riboswitch is the smallest representative of the ykkC class with the mechanism of its function being centred on the idea that its two stem loops P1 and P2 form a kissing hairpin interaction upon binding of guanidinium (Gdm+). This mechanism is based on in-line probing experiments with the full-length riboswitch and crystal structures of the truncated stem loops P1 and P2. However, the crystal structures reveal only the formation of the homodimers P1 | P1 and P2 | P2 but not of the proposed heterodimer P1 | P2. Here, site-directed spin labeling (SDSL) in combination with Pulsed Electron–Electron Double Resonance (PELDOR or DEER) is used to study their structures in solution and how they change upon binding of Gdm+. It is found that both hairpins adopt different structures in solution and that binding of Gdm+ does indeed lead to the formation of the heterodimer but alongside the homodimers in a statistical 1:2:1 fashion. These results do thus support the proposed switching mechanism.
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Affiliation(s)
- Christine Wuebben
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115 Bonn, Germany
| | - Maria F Vicino
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115 Bonn, Germany
| | - Marcel Mueller
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115 Bonn, Germany
| | - Olav Schiemann
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115 Bonn, Germany
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9
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Sherck N, Webber T, Brown DR, Keller T, Barry M, DeStefano A, Jiao S, Segalman RA, Fredrickson GH, Shell MS, Han S. End-to-End Distance Probability Distributions of Dilute Poly(ethylene oxide) in Aqueous Solution. J Am Chem Soc 2020; 142:19631-19641. [DOI: 10.1021/jacs.0c08709] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Nicholas Sherck
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Thomas Webber
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Dennis Robinson Brown
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Timothy Keller
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Mikayla Barry
- Department of Materials, University of California, Santa Barbara, California 93106, United States
| | - Audra DeStefano
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Sally Jiao
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Rachel A. Segalman
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
- Department of Materials, University of California, Santa Barbara, California 93106, United States
| | - Glenn H. Fredrickson
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
- Department of Materials, University of California, Santa Barbara, California 93106, United States
- Materials Research Laboratory, University of California, Santa Barbara, California 93106, United States
| | - M. Scott Shell
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Songi Han
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
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10
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Wili N, Hintz H, Vanas A, Godt A, Jeschke G. Distance measurement between trityl radicals by pulse dressed electron paramagnetic resonance with phase modulation. MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2020; 1:75-87. [PMID: 37904888 PMCID: PMC10500722 DOI: 10.5194/mr-1-75-2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 04/29/2020] [Indexed: 11/01/2023]
Abstract
Distance measurement in the nanometre range is among the most important applications of pulse electron paramagnetic resonance today, especially in biological applications. The longest distance that can be measured by all presently used pulse sequences is determined by the phase memory time T m of the observed spins. Here we show that one can measure the dipolar coupling during strong microwave irradiation by using an appropriate frequency- or phase-modulation scheme, i.e. by applying pulse sequences in the nutating frame. This decouples the electron spins from the surrounding nuclear spins and thus leads to significantly longer relaxation times of the microwave-dressed spins (i.e. the rotating frame relaxation times T 1 ρ and T 2 ρ ) compared to T m . The electron-electron dipolar coupling is not decoupled as long as both spins are excited, which can be implemented for trityl radicals at Q-band frequencies (35 GHz, 1.2 T). We show results for two bis-trityl rulers with inter-electron distances of about 4.1 and 5.3 nm and discuss technical challenges and possible next steps.
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Affiliation(s)
- Nino Wili
- Department of Chemistry and Applied Biosciences, Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Henrik Hintz
- Faculty of Chemistry and Center for Molecular Materials (CM2), Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld, Germany
| | - Agathe Vanas
- Department of Chemistry and Applied Biosciences, Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Adelheid Godt
- Faculty of Chemistry and Center for Molecular Materials (CM2), Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld, Germany
| | - Gunnar Jeschke
- Department of Chemistry and Applied Biosciences, Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
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11
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Bücker D, Sickinger A, Ruiz Perez JD, Oestringer M, Mecking S, Drescher M. Direct Observation of Chain Lengths and Conformations in Oligofluorene Distributions from Controlled Polymerization by Double Electron–Electron Resonance. J Am Chem Soc 2019; 142:1952-1956. [DOI: 10.1021/jacs.9b11404] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Dennis Bücker
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Annika Sickinger
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Julian D. Ruiz Perez
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Manuel Oestringer
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Stefan Mecking
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Malte Drescher
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
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12
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Hattori Y, Nishimura N, Tsutsui Y, Ghosh S, Sakurai T, Sugiyasu K, Takeuchi M, Seki S. Rod-like transition first or chain aggregation first? ordered aggregation of rod-like poly(p-phenyleneethynylene) chains in solution. Chem Commun (Camb) 2019; 55:13342-13345. [PMID: 31626266 DOI: 10.1039/c9cc06892a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The rod-like configuration of conjugated polymer chains with its low energetic disorder is the key to utilizing the backbone as a highly electrically-conductive wire. An energetic disorder that is higher than 0.1 eV, coupled with vibronic modes of the chains, leads to the localization of charges. Herein, we have tracked precisely the rod-like transition of poly(p-phenyleneethynylene) (PPE) chains as a function of temperature in diluted solutions, and shown a steep increase in persistence length at 230 K. The resulting rod-like configuration of the PPE chains with its extended electronic conjugation exhibited an extremely small energetic disorder of ∼70 meV, and was stabilized by subsequent polymer aggregate formation.
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Affiliation(s)
- Yusuke Hattori
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan.
| | - Nozomi Nishimura
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan.
| | - Yusuke Tsutsui
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan.
| | - Samrat Ghosh
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan.
| | - Tsuneaki Sakurai
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan.
| | - Kazunori Sugiyasu
- Molecular Design & Function Group, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba 305-0047, Japan
| | - Masayuki Takeuchi
- Molecular Design & Function Group, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba 305-0047, Japan
| | - Shu Seki
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan.
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13
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Dwarkanath N, Palchowdhury S, Balasubramanian S. Unraveling the Sorption Mechanism of CO 2 in a Molecular Crystal without Intrinsic Porosity. J Phys Chem B 2019; 123:7471-7481. [PMID: 31368698 DOI: 10.1021/acs.jpcb.9b05999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The facile uptake of CO2 gas in a nonporous molecular crystal constituted by long molecules with carbazole and ethynylphenyl moieties was reported in experiments recently. Herein, the mechanism of gas uptake by this crystal is elucidated using atomistic molecular simulations. The uptake of CO2 is shown to be facilitated by (i) the capacity of the crystal to expand in volume because of weak intermolecular interactions, (ii) the parallel orientation of the long molecules in the crystal, and (iii) the ability of the molecule to marginally bend, yet not lose crystallinity because of the anchoring of the terminal carbazole groups. The retention of crystallinity upon sorption and desorption cycles is also demonstrated. At high enough pressures, near-neighbor CO2 molecules sorbed in the crystal are found to be oriented parallel to each other.
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Affiliation(s)
- Nimish Dwarkanath
- Chemistry and Physics of Materials Unit , Jawaharlal Nehru Centre for Advanced Scientific Research , Bangalore 560 064 , India
| | - Sourav Palchowdhury
- Chemistry and Physics of Materials Unit , Jawaharlal Nehru Centre for Advanced Scientific Research , Bangalore 560 064 , India
| | - S Balasubramanian
- Chemistry and Physics of Materials Unit , Jawaharlal Nehru Centre for Advanced Scientific Research , Bangalore 560 064 , India
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14
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Rein S, Lewe P, Andrade SL, Kacprzak S, Weber S. Global analysis of complex PELDOR time traces. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 295:17-26. [PMID: 30092553 DOI: 10.1016/j.jmr.2018.07.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 07/20/2018] [Accepted: 07/21/2018] [Indexed: 05/24/2023]
Abstract
Pulsed electron-electron double resonance (PELDOR, alternatively called DEER for double electron-electron resonance) pulse sequences allow for the detection of echo decay curves that are modulated by dipole-dipole-coupling frequencies of interacting electron spins. With increasing distance between them, the echo decay needs to be monitored over a progressively extended time period. However, since the echo intensity typically falls off exponentially with increasing time, this might be problematic with respect to the minimum signal-to-noise ratio required for a sound data analysis. In this contribution we present the new PELDOR analysis tool GloPel (Global analysis of PELDOR data), an open-source Python-based application, that allows to extract improved-quality distance distributions from PELDOR data for which no ideal signal-to-noise ratio can be achieved for a very long observation window. By using Tikhonov regularization, GloPel allows for the simultaneous analysis of two time traces acquired for a sample in two different observation time windows, thus taking advantage of both, the typically high signal-to-noise ratio of the time trace acquired at early times of the echo decay, and the best possible background function fitted for the decay at later times, which is in most cases superimposed with considerable noise. In this way, short distances are not overseen in the higher noise of the longer time traces while long distances are not artificially shortened by limiting the observation time window of the experiment. Following our suggested data acquisition procedure, a significant reduction of the measurement time may also be achieved.
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Affiliation(s)
- Stephan Rein
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Philipp Lewe
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany
| | - Susana L Andrade
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universität Freiburg, Schänzlestr. 18, 79104 Freiburg, Germany
| | - Sylwia Kacprzak
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany.
| | - Stefan Weber
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany.
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15
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Pan Y, Neupane S, Farmakes J, Oh M, Bentz K, Choi Y, Yang Z. Insights on the Structure, Molecular Weight and Activity of an Antibacterial Protein-Polymer Hybrid. Chemphyschem 2018; 19:651-658. [PMID: 29131929 PMCID: PMC6122959 DOI: 10.1002/cphc.201701097] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Indexed: 12/11/2022]
Abstract
Protein-polymer conjugates are attractive biomaterials which combine the functions of both proteins and polymers. The bioactivity of these hybrid materials, however, is often reduced upon conjugation. It is important to determine and monitor the protein structure and active site availability in order to optimize the polymer composition, attachment point, and abundance. The challenges in probing these insights are the large size and high complexity in the conjugates. Herein, we overcome the challenges by combining electron paramagnetic resonance (EPR) spectroscopy and atomic force microscopy (AFM) and characterize the structure of antibacterial hybrids formed by polyethylene glycol (PEG) and an antibacterial protein. We discovered that the primary reasons for activity loss were PEG blocking the substrate access pathway and/or altering protein surface charges. Our data indicated that the polymers tended to stay away from the protein surface and form a coiled conformation. The structural insights are meaningful for and applicable to the rational design of future hybrids.
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Affiliation(s)
- Yanxiong Pan
- Department of Chemistry and Biochemistry, North Dakota State University, 1231 Albrecht Blvd, Fargo, ND, 58108 (USA),
| | - Sunanda Neupane
- Department of Chemistry and Biochemistry, North Dakota State University, 1231 Albrecht Blvd, Fargo, ND, 58108 (USA),
| | - Jasmin Farmakes
- Department of Chemistry and Biochemistry, North Dakota State University, 1231 Albrecht Blvd, Fargo, ND, 58108 (USA),
| | - Myungkeun Oh
- Materials and Nanotechnology Program, North Dakota State University, 251 Batcheller Technology Center, Fargo, ND 58105
| | - Kylie Bentz
- Department of Chemistry and Biochemistry, North Dakota State University, 1231 Albrecht Blvd, Fargo, ND, 58108 (USA),
| | - Yongki Choi
- Materials and Nanotechnology Program, North Dakota State University, 251 Batcheller Technology Center, Fargo, ND 58105
- Department of Physics, North Dakota State University, 1211 Albrecht Blvd, Fargo, ND, 58108 (USA),
| | - Zhongyu Yang
- Department of Chemistry and Biochemistry, North Dakota State University, 1231 Albrecht Blvd, Fargo, ND, 58108 (USA),
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16
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Grytz CM, Kazemi S, Marko A, Cekan P, Güntert P, Sigurdsson ST, Prisner TF. Determination of helix orientations in a flexible DNA by multi-frequency EPR spectroscopy. Phys Chem Chem Phys 2018; 19:29801-29811. [PMID: 29090294 DOI: 10.1039/c7cp04997h] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Distance measurements are performed between a pair of spin labels attached to nucleic acids using Pulsed Electron-Electron Double Resonance (PELDOR, also called DEER) spectroscopy which is a complementary tool to other structure determination methods in structural biology. The rigid spin label Ç, when incorporated pairwise into two helical parts of a nucleic acid molecule, allows the determination of both the mutual orientation and the distance between those labels, since Ç moves rigidly with the helix to which it is attached. We have developed a two-step protocol to investigate the conformational flexibility of flexible nucleic acid molecules by multi-frequency PELDOR. In the first step, a library with a broad collection of conformers, which are in agreement with topological constraints, NMR restraints and distances derived from PELDOR, was created. In the second step, a weighted structural ensemble of these conformers was chosen, such that it fits the multi-frequency PELDOR time traces of all doubly Ç-labelled samples simultaneously. This ensemble reflects the global structure and the conformational flexibility of the two-way DNA junction. We demonstrate this approach on a flexible bent DNA molecule, consisting of two short helical parts with a five adenine bulge at the center. The kink and twist motions between both helical parts were quantitatively determined and showed high flexibility, in agreement with a Förster Resonance Energy Transfer (FRET) study on a similar bent DNA motif. The approach presented here should be useful to describe the relative orientation of helical motifs and the conformational flexibility of nucleic acid structures, both alone and in complexes with proteins and other molecules.
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Affiliation(s)
- C M Grytz
- Institute of Physical and Theoretical Chemistry, Goethe University, Max-von-Laue-Str. 7, 60438 Frankfurt am Main, Germany.
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17
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Stelzl LS, Erlenbach N, Heinz M, Prisner TF, Hummer G. Resolving the Conformational Dynamics of DNA with Ångstrom Resolution by Pulsed Electron-Electron Double Resonance and Molecular Dynamics. J Am Chem Soc 2017; 139:11674-11677. [PMID: 28777549 DOI: 10.1021/jacs.7b05363] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pulsed electron-electron double resonance (PELDOR/DEER) experiments of nucleic acids with rigid spin labels provide highly accurate distance and orientation information. Here we combine PELDOR experiments with molecular dynamics (MD) simulations to arrive at an atomistic view of the conformational dynamics of DNA. The MD simulations closely reproduce the PELDOR time traces, and demonstrate that bending, in addition to twist-stretch motions, underpin the sub-μs dynamics of DNA. PELDOR experiments correctly rank DNA force fields and resolve subtle differences in the conformational ensembles of nucleic acids, on the order of 1-2 Å. Long-range distance and angle measurements with rigid spin labels provide critical input for the refinement of computer models and the elucidation of the structure and dynamics of complex biomolecules.
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Affiliation(s)
- Lukas S Stelzl
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics , 60438 Frankfurt am Main, Germany
| | - Nicole Erlenbach
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt , 60438 Frankfurt am Main, Germany
| | - Marcel Heinz
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics , 60438 Frankfurt am Main, Germany
| | - Thomas F Prisner
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt , 60438 Frankfurt am Main, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics , 60438 Frankfurt am Main, Germany.,Institute for Biophysics, Goethe University Frankfurt , 60438 Frankfurt am Main, Germany
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18
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Aguilar-Granda A, Pérez-Estrada S, Sánchez-González E, Álvarez JR, Rodríguez-Hernández J, Rodríguez M, Roa AE, Hernández-Ortega S, Ibarra IA, Rodríguez-Molina B. Transient Porosity in Densely Packed Crystalline Carbazole–(p-Diethynylphenylene)–Carbazole Rotors: CO2 and Acetone Sorption Properties. J Am Chem Soc 2017; 139:7549-7557. [DOI: 10.1021/jacs.7b02015] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Salvador Pérez-Estrada
- Department
of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | | | | | - Joelis Rodríguez-Hernández
- Centro de Investigación en Química Aplicada (CIQA), Blvd. Enrique Reyna Hermosillo,
No. 140, Saltillo, Coahuila 25294, México
| | - Mario Rodríguez
- Centro de Investigaciones en Óptica, A.P. 1-948, León, Guanajuato 37000, México
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19
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Idelson A, Sterzenbach C, Jester SS, Tschierske C, Baumeister U, Höger S. A Liquid-Crystalline Phenylene-Based Shape-Persistent Molecular Spoked Wheel. J Am Chem Soc 2017; 139:4429-4434. [PMID: 28248519 DOI: 10.1021/jacs.6b13020] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecular spoked wheels with an all-phenylene backbone and different alkoxy side chain substitution patterns were synthesized using a cobalt-catalyzed [2 + 2 + 2] cycloaddition and subsequent template-directed cyclization via Yamamoto coupling. The two-dimensional organization of the molecules at the solid/liquid interface was investigated by means of scanning tunneling microscopy, allowing imaging of the molecular structure with submolecular resolution. With the right proportion of the flexible alkyl corona to the rigid core, mesomorphic behavior of one compound could be observed over a wide temperature range.
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Affiliation(s)
- Alissa Idelson
- Kekulé-Institut für Organische Chemie und Biochemie, Rheinische Friedrichs-Wilhelms-Universität Bonn , Gerhard-Domagk-Str. 1, 53121 Bonn, Germany
| | - Christopher Sterzenbach
- Kekulé-Institut für Organische Chemie und Biochemie, Rheinische Friedrichs-Wilhelms-Universität Bonn , Gerhard-Domagk-Str. 1, 53121 Bonn, Germany
| | - Stefan-S Jester
- Kekulé-Institut für Organische Chemie und Biochemie, Rheinische Friedrichs-Wilhelms-Universität Bonn , Gerhard-Domagk-Str. 1, 53121 Bonn, Germany
| | - Carsten Tschierske
- Institut für Chemie, Organische Chemie, Martin-Luther-Universität Halle-Wittenberg , Kurt-Mothes-Strasse 2, 06120 Halle (Saale), Germany
| | - Ute Baumeister
- Institut für Chemie, Physikalische Chemie, Martin-Luther-Universität Halle-Wittenberg , Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany
| | - Sigurd Höger
- Kekulé-Institut für Organische Chemie und Biochemie, Rheinische Friedrichs-Wilhelms-Universität Bonn , Gerhard-Domagk-Str. 1, 53121 Bonn, Germany
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20
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Pan Y, Neupane S, Farmakes J, Bridges M, Froberg J, Rao J, Qian SY, Liu G, Choi Y, Yang Z. Probing the structural basis and adsorption mechanism of an enzyme on nano-sized protein carriers. NANOSCALE 2017; 9:3512-3523. [PMID: 28244542 DOI: 10.1039/c7nr00276a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Silica nanoparticles (SiNPs) are important nano-sized, solid-state carriers/hosts to load, store, and deliver biological or pharmaceutical cargoes. They are also good potential solid supports to immobilize proteins for fundamental protein structure and dynamics studies. However, precaution is necessary when using SiNPs in these areas because adsorption might alter the activity of the cargoes, especially when enzymes are loaded. Therefore, it becomes important to understand the structural basis of the cargo enzyme activity changes, if there is any. The high complexity and dynamics of the nano-bio interface present many challenges. Reported here is a comprehensive study of the structure, dynamics, and activity of a model enzyme, T4 lysozyme, upon adsorption to a few surface-modified SiNPs using several experimental techniques. Not surprisingly, a significant activity loss on each studied SiNP was found. The structural basis of the activity loss was identified based on results from a unique technique, the Electron Paramagnetic Resonance (EPR) spectroscopy, which probes structural information regardless of the complexity. Several docking models of the enzyme on SiNPs with different surfaces, at different enzyme-to-SiNP ratios are proposed. Interestingly, we found that the adsorbed enzyme can be desorbed via pH adjustment, which highlighted the potential to use SiNPs for enzyme/protein delivery or storage due to the high capacity. In order to use SiNPs as enzyme hosts, minimizing the enzymatic activity loss upon adsorption is needed. Lastly, the work outlined here demonstrate the use of EPR in probing structural information on the complex (inorganic)nano-bio interface.
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Affiliation(s)
- Yanxiong Pan
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA.
| | - Sunanda Neupane
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA.
| | - Jasmin Farmakes
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA.
| | - Michael Bridges
- Jules Stein Eye Institute, University of California, Los Angeles, CA 90025, USA
| | - James Froberg
- Department of Physics, North Dakota State University, Fargo, ND 58108, USA
| | - Jiajia Rao
- Department of Plant Sciences, North Dakota State University, Fargo, ND 58108, USA
| | - Steven Y Qian
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, ND 58108, USA
| | - Guodong Liu
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA.
| | - Yongki Choi
- Department of Physics, North Dakota State University, Fargo, ND 58108, USA
| | - Zhongyu Yang
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA.
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21
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Clayton JA, Qi M, Godt A, Goldfarb D, Han S, Sherwin MS. Gd 3+-Gd 3+ distances exceeding 3 nm determined by very high frequency continuous wave electron paramagnetic resonance. Phys Chem Chem Phys 2017; 19:5127-5136. [PMID: 28139788 PMCID: PMC5394103 DOI: 10.1039/c6cp07119h] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electron paramagnetic resonance spectroscopy in combination with site-directed spin labeling is a very powerful tool for elucidating the structure and organization of biomolecules. Gd3+ complexes have recently emerged as a new class of spin labels for distance determination by pulsed EPR spectroscopy at Q- and W-band. We present CW EPR measurements at 240 GHz (8.6 Tesla) on a series of Gd-rulers of the type Gd-PyMTA-spacer-Gd-PyMTA, with Gd-Gd distances ranging from 1.2 nm to 4.3 nm. CW EPR measurements of these Gd-rulers show that significant dipolar broadening of the central |-1/2〉 → |1/2〉 transition occurs at 30 K for Gd-Gd distances up to ∼3.4 nm with Gd-PyMTA as the spin label. This represents a significant extension for distances accessible by CW EPR, as nitroxide-based spin labels at X-band frequencies can typically only access distances up to ∼2 nm. We show that this broadening persists at biologically relevant temperatures above 200 K, and that this method is further extendable up to room temperature by immobilizing the sample in glassy trehalose. We show that the peak-to-peak broadening of the central transition follows the expected 1/r3 dependence for the electron-electron dipolar interaction, from cryogenic temperatures up to room temperature. A simple procedure for simulating the dependence of the lineshape on interspin distance is presented, in which the broadening of the central transition is modeled as an S = 1/2 spin whose CW EPR lineshape is broadened through electron-electron dipolar interactions with a neighboring S = 7/2 spin.
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Affiliation(s)
- Jessica A Clayton
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, USA. and Institute for Terahertz Science and Technology, University of California, Santa Barbara, Santa Barbara, CA, USA
| | - Mian Qi
- Faculty of Chemistry and Center for Molecular Materials (CM2), Bielefeld University, Bielefeld, Germany
| | - Adelheid Godt
- Faculty of Chemistry and Center for Molecular Materials (CM2), Bielefeld University, Bielefeld, Germany
| | - Daniella Goldfarb
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Songi Han
- Institute for Terahertz Science and Technology, University of California, Santa Barbara, Santa Barbara, CA, USA and Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA, USA and Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, CA, USA
| | - Mark S Sherwin
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, USA. and Institute for Terahertz Science and Technology, University of California, Santa Barbara, Santa Barbara, CA, USA
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22
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Hintze C, Korf P, Degen F, Schütze F, Mecking S, Steiner UE, Drescher M. Delocalization of Coherent Triplet Excitons in Linear Rigid Rod Conjugated Oligomers. J Phys Chem Lett 2017; 8:690-695. [PMID: 28107011 DOI: 10.1021/acs.jpclett.6b02869] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In this work, the triplet state delocalization in a series of monodisperse oligo(p-phenyleneethynylene)s (OPEs) is studied by pulsed electron paramagnetic resonance (EPR) and pulsed electron nuclear double resonance (ENDOR) determining zero-field splitting, optical spin polarization, and proton hyperfine couplings. Neither the zero-field splitting parameters nor the optical spin polarization change significantly with OPE chain length, in contrast to the hyperfine coupling constants, which showed a systematic decrease with chain length n according to a 2/(1 + n) decay law. The results provide striking evidence for the Frenkel-type nature of the triplet excitons exhibiting full coherent delocalization in the OPEs under investigation with up to five OPE repeat units and with a spin density distribution described by a nodeless particle in the box wave function. The same model is successfully applied to recently published data on π-conjugated porphyrin oligomers.
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Affiliation(s)
- Christian Hintze
- Fachbereich Chemie, Universität Konstanz , 78457 Konstanz, Germany
| | - Patrick Korf
- Fachbereich Chemie, Universität Konstanz , 78457 Konstanz, Germany
| | - Frank Degen
- Fachbereich Chemie, Universität Konstanz , 78457 Konstanz, Germany
| | | | - Stefan Mecking
- Fachbereich Chemie, Universität Konstanz , 78457 Konstanz, Germany
| | - Ulrich E Steiner
- Fachbereich Chemie, Universität Konstanz , 78457 Konstanz, Germany
| | - Malte Drescher
- Fachbereich Chemie, Universität Konstanz , 78457 Konstanz, Germany
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23
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Brown JS, Acevedo YM, He GD, Freed JH, Clancy P, Alabi CA. Synthesis and Solution-Phase Characterization of Sulfonated Oligothioetheramides. Macromolecules 2017; 50:8731-8738. [PMID: 29386690 PMCID: PMC5788177 DOI: 10.1021/acs.macromol.7b01915] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Nature has long demonstrated the importance of chemical sequence to induce structure and tune physical interactions. Investigating macromolecular structure and dynamics is paramount to understand macromolecular binding and target recognition. To that end, we have synthesized and characterized flexible sulfonated oligothioetheramides (oligo-TEAs) by variable temperature pulse field gradient (PFG) NMR, double electron-electron resonance (DEER), and molecular dynamics (MD) simulations to capture their room temperature structure and dynamics in water. We have examined the contributions of synthetic length (2-12mer), pendant group charge, and backbone hydrophobicity. We observe significant entropic collapse, driven in part by backbone hydrophobicity. Analysis of individual monomer contributions revealed larger changes due to the backbone compared to pendant groups. We also observe screening of intramolecular electrostatic repulsions. Finally, we comment on the combination of DEER and PFG NMR measurements via Stokes-Einstein-Sutherland diffusion theory. Overall, this sensitive characterization holds promise to enable de novo development of macromolecular structure and sequence-structure-function relationships with flexible, but biologically functional macromolecules.
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Affiliation(s)
- Joseph S. Brown
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14850, United States
| | - Yaset M. Acevedo
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14850, United States
| | - Grace D. He
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14850, United States
| | - Jack H. Freed
- Department of Chemistry and Chemical Biology and National Biomedical Center for Advanced ESR Technology, Cornell University, Ithaca, New York 14853, United States
| | - Paulette Clancy
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14850, United States
| | - Christopher A. Alabi
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14850, United States
- Department of Chemistry and Chemical Biology and National Biomedical Center for Advanced ESR Technology, Cornell University, Ithaca, New York 14853, United States
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24
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Kao TY, Tsai CJ, Lan YJ, Chiang YW. The role of conformational heterogeneity in regulating the apoptotic activity of BAX protein. Phys Chem Chem Phys 2017; 19:9584-9591. [DOI: 10.1039/c7cp00401j] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Inactive BAX exists in two states. A shift in the equilibrium would initiate apoptosis.
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Affiliation(s)
- Te-Yu Kao
- Department of Chemistry
- National Tsing Hua University
- Hsinchu 30013
- Taiwan
| | - Chia-Jung Tsai
- Department of Chemistry
- National Tsing Hua University
- Hsinchu 30013
- Taiwan
| | - Yu-Jing Lan
- Department of Chemistry
- National Tsing Hua University
- Hsinchu 30013
- Taiwan
| | - Yun-Wei Chiang
- Department of Chemistry
- National Tsing Hua University
- Hsinchu 30013
- Taiwan
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25
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Grytz CM, Marko A, Cekan P, Sigurdsson ST, Prisner TF. Flexibility and conformation of the cocaine aptamer studied by PELDOR. Phys Chem Chem Phys 2016; 18:2993-3002. [PMID: 26740459 DOI: 10.1039/c5cp06158j] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The cocaine aptamer is a DNA three-way junction that binds cocaine at its helical junction. We studied the global conformation and overall flexibility of the aptamer in the absence and presence of cocaine by pulsed electron-electron double resonance (PELDOR) spectroscopy, also called double electron-electron resonance (DEER). The rigid nitroxide spin label Ç was incorporated pairwise into two helices of the aptamer. Multi-frequency 2D PELDOR experiments allow the determination of the mutual orientation and the distances between two Çs. Since Ç is rigidly attached to double-stranded DNA, it directly reports on the aptamer dynamics. The cocaine-bound and the non-bound states could be differentiated by their conformational flexibility, which decreases upon binding to cocaine. We observed a small change in the width and mean value of the distance distribution between the two spin labels upon cocaine binding. Further structural insights were obtained by investigating the relative orientation between the two spin-labeled stems of the aptamer. We determined the bend angle between this two stems. By combining the orientation information with a priori knowledge about the secondary structure of the aptamer, we obtained a molecular model describing the global folding and flexibility of the cocaine aptamer.
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Affiliation(s)
- C M Grytz
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University, 60438 Frankfurt am Main, Max-von-Laue-Str. 9, Hessen, Germany.
| | - A Marko
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University, 60438 Frankfurt am Main, Max-von-Laue-Str. 9, Hessen, Germany.
| | - P Cekan
- University of Iceland, Department of Chemistry, Science Institute, Dunhaga 3, 107 Reykjavik, Iceland.
| | - S Th Sigurdsson
- University of Iceland, Department of Chemistry, Science Institute, Dunhaga 3, 107 Reykjavik, Iceland.
| | - T F Prisner
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University, 60438 Frankfurt am Main, Max-von-Laue-Str. 9, Hessen, Germany.
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26
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Demay-Drouhard P, Ching HYV, Akhmetzyanov D, Guillot R, Tabares LC, Bertrand HC, Policar C. A Bis-Manganese(II)-DOTA Complex for Pulsed Dipolar Spectroscopy. Chemphyschem 2016; 17:2066-78. [DOI: 10.1002/cphc.201600234] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Indexed: 12/16/2022]
Affiliation(s)
- Paul Demay-Drouhard
- Ecole Normale Supérieure-PSL Research University; Département de Chimie, Sorbonne Universités-UPMC Univ Paris 06; CNRS UMR 7203 LBM; 24 rue Lhomond 75005 Paris France
| | - H. Y. Vincent Ching
- Institute for Integrative Biology of the Cell (I2BC); Department of Biochemistry, Biophysics and Structural Biology; Université Paris-Saclay, CEA, CNRS UMR 9198; Gif-sur-Yvette F-91198 France
| | - Dmitry Akhmetzyanov
- Goethe-University Frankfurt am Main; Institute of Physical and Theoretical Chemistry and; Center for Biomolecular Magnetic Resonance; Max von Laue Str. 7 60438 Frankfurt am Main Germany
| | - Régis Guillot
- Institut de Chimie Moléculaire et des Matériaux O'Orsay; Université Paris-Sud, UMR CNRS 8182, Université Paris-Saclay; 91405 Orsay France
| | - Leandro C. Tabares
- Institute for Integrative Biology of the Cell (I2BC); Department of Biochemistry, Biophysics and Structural Biology; Université Paris-Saclay, CEA, CNRS UMR 9198; Gif-sur-Yvette F-91198 France
| | - Hélène C. Bertrand
- Ecole Normale Supérieure-PSL Research University; Département de Chimie, Sorbonne Universités-UPMC Univ Paris 06; CNRS UMR 7203 LBM; 24 rue Lhomond 75005 Paris France
| | - Clotilde Policar
- Ecole Normale Supérieure-PSL Research University; Département de Chimie, Sorbonne Universités-UPMC Univ Paris 06; CNRS UMR 7203 LBM; 24 rue Lhomond 75005 Paris France
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27
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Stevens MA, McKay JE, Robinson JLS, El Mkami H, Smith GM, Norman DG. The use of the Rx spin label in orientation measurement on proteins, by EPR. Phys Chem Chem Phys 2016; 18:5799-806. [PMID: 26426572 PMCID: PMC4756314 DOI: 10.1039/c5cp04753f] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 09/25/2015] [Indexed: 12/15/2022]
Abstract
The bipedal spin label Rx is more restricted in its conformation and dynamics than its monopodal counterpart R1. To systematically investigate the utility of the Rx label, we have attempted to comprehensively survey the attachment of Rx to protein secondary structures. We have examined the formation, structure and dynamics of the spin label in relation to the underlying protein in order to determine feasibility and optimum conditions for distance and orientation measurement by pulsed EPR. The labeled proteins have been studied using molecular dynamics, CW EPR, pulsed EPR distance measurement at X-band and orientation measurement at W-band. The utility of different modes and positions of attachment have been compared and contrasted.
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Affiliation(s)
- M A Stevens
- Nucleic Acid Structure Research Group, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK.
| | - J E McKay
- School of Physics and Astronomy, University of St Andrews, St. Andrews, KY16 9SS, UK
| | - J L S Robinson
- Nucleic Acid Structure Research Group, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK.
| | - H El Mkami
- School of Physics and Astronomy, University of St Andrews, St. Andrews, KY16 9SS, UK
| | - G M Smith
- School of Physics and Astronomy, University of St Andrews, St. Andrews, KY16 9SS, UK
| | - D G Norman
- Nucleic Acid Structure Research Group, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK.
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28
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Ackermann K, Giannoulis A, Cordes DB, Slawin AMZ, Bode BE. Assessing dimerisation degree and cooperativity in a biomimetic small-molecule model by pulsed EPR. Chem Commun (Camb) 2016; 51:5257-60. [PMID: 25587579 DOI: 10.1039/c4cc08656b] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Pulsed electron paramagnetic resonance (EPR) spectroscopy is gaining increasing importance as a complementary biophysical technique in structural biology. Here, we describe the synthesis, optimisation, and EPR titration studies of a spin-labelled terpyridine Zn(II) complex serving as a small-molecule model system for tuneable dimerisation.
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Affiliation(s)
- K Ackermann
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK.
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29
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Bowen AM, Jones MW, Lovett JE, Gaule TG, McPherson MJ, Dilworth JR, Timmel CR, Harmer JR. Exploiting orientation-selective DEER: determining molecular structure in systems containing Cu(ii) centres. Phys Chem Chem Phys 2016; 18:5981-94. [DOI: 10.1039/c5cp06096f] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Analysis of orientation-selective DEER measurements using Cu(ii) centres in a series of molecules demonstrates its limits and capabilities in structure elucidation.
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Affiliation(s)
- Alice M. Bowen
- Centre for Advanced Electron Spin Resonance
- University of Oxford
- Oxford
- UK
- Institute of Physical and Theoretical Chemistry
| | - Michael W. Jones
- Centre for Advanced Electron Spin Resonance
- University of Oxford
- Oxford
- UK
| | - Janet E. Lovett
- Centre for Advanced Electron Spin Resonance
- University of Oxford
- Oxford
- UK
- SUPA
| | - Thembanikosi G. Gaule
- Astbury Centre for Structural Molecular Biology
- Institute of Molecular and Cellular Biology
- Faculty of Biological Sciences
- University of Leeds
- Leeds LS2 9JT
| | - Michael J. McPherson
- Astbury Centre for Structural Molecular Biology
- Institute of Molecular and Cellular Biology
- Faculty of Biological Sciences
- University of Leeds
- Leeds LS2 9JT
| | | | | | - Jeffrey R. Harmer
- Centre for Advanced Electron Spin Resonance
- University of Oxford
- Oxford
- UK
- Centre for Advanced Imaging
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30
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Doll A, Qi M, Wili N, Pribitzer S, Godt A, Jeschke G. Gd(III)-Gd(III) distance measurements with chirp pump pulses. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 259:153-62. [PMID: 26340436 DOI: 10.1016/j.jmr.2015.08.010] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 08/13/2015] [Accepted: 08/14/2015] [Indexed: 05/15/2023]
Abstract
The broad EPR spectrum of Gd(III) spin labels restricts the dipolar modulation depth in distance measurements between Gd(III) pairs to a few percent. To overcome this limitation, frequency-swept chirp pulses are utilized as pump pulses in the DEER experiment. Using a model system with 3.4 nm Gd-Gd distance, application of one single chirp pump pulse at Q-band frequencies leads to modulation depths beyond 10%. However, the larger modulation depth is counteracted by a reduction of the absolute echo intensity due to the pump pulse. As supported by spin dynamics simulations, this effect is primarily driven by signal loss to double-quantum coherence and specific to the Gd(III) high spin state of S=7/2. In order to balance modulation depth and echo intensity for optimum sensitivity, a simple experimental procedure is proposed. An additional improvement by 25% in DEER sensitivity is achieved with two consecutive chirp pump pulses. These pulses pump the Gd(III) spectrum symmetrically around the observation position, therefore mutually compensating for dynamical Bloch-Siegert phase shifts at the observer spins. The improved sensitivity of the DEER data with modulation depths on the order of 20% is due to mitigation of the echo reduction effects by the consecutive pump pulses. In particular, the second pump pulse does not lead to additional signal loss if perfect inversion is assumed. Moreover, the compensation of the dynamical Bloch-Siegert phase prevents signal loss due to spatial dependence of the dynamical phase, which is caused by inhomogeneities in the driving field. The new methodology is combined with pre-polarization techniques to measure long distances up to 8.6 nm, where signal intensity and modulation depth become attenuated by long dipolar evolution windows. In addition, the influence of the zero-field splitting parameters on the echo intensity is studied with simulations. Herein, larger sensitivity is anticipated for Gd(III) complexes with zero-field splitting that is smaller than for the employed Gd-PyMTA complex.
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Affiliation(s)
- Andrin Doll
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
| | - Mian Qi
- Faculty of Chemistry and Center for Molecular Materials, Bielefeld University, Unversitätsstraße 25, 33615 Bielefeld, Germany
| | - Nino Wili
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
| | - Stephan Pribitzer
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
| | - Adelheid Godt
- Faculty of Chemistry and Center for Molecular Materials, Bielefeld University, Unversitätsstraße 25, 33615 Bielefeld, Germany
| | - Gunnar Jeschke
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland.
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31
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Garbuio L, Lewandowski B, Wilhelm P, Ziegler L, Yulikov M, Wennemers H, Jeschke G. Shape Persistence of Polyproline II Helical Oligoprolines. Chemistry 2015; 21:10747-53. [PMID: 26089127 DOI: 10.1002/chem.201501190] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Indexed: 11/06/2022]
Abstract
Oligoprolines are commonly used as molecular scaffolds. Past studies on the persistence length of their secondary structure, the polyproline II (PPII) helix, and on the fraction of backbone cis amide bonds have provided conflicting results. We resolved this debate by studying a series of spin-labeled proline octadecamers with EPR spectroscopy. Distance distributions between an N-terminal Gd(III) -DOTA (DOTA=1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) label and a nitroxide label at one of five evenly spaced backbone sites allowed us to discriminate between the flexibility of the PPII helix and the cis amide contributions. An upper limit of 2 % cis amide bonds per residue was found in a 7:3 (v/v) water/glycerol mixture, whereas cis amides were not observed in trifluoroethanol. Extrapolation of Monte Carlo models from the glass transition to ambient temperature predicts a persistence length of ≈3-3.5 nm in both solvents. The method is generally applicable to any type of oligomer for which the persistence length is of interest.
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Affiliation(s)
- Luca Garbuio
- ETH Zurich, Department of Chemistry and Applied Bioscience, Laboratory of Physical Chemistry, Vladimir Prelog Weg 2, 8093, Zurich (Switzerland)
| | - Bartosz Lewandowski
- ETH Zurich, Department of Chemistry and Applied Bioscience, Laboratory of Organic Chemistry, Vladimir Prelog Weg 3, 8093, Zurich (Switzerland)
| | - Patrick Wilhelm
- ETH Zurich, Department of Chemistry and Applied Bioscience, Laboratory of Organic Chemistry, Vladimir Prelog Weg 3, 8093, Zurich (Switzerland)
| | - Ludmila Ziegler
- ETH Zurich, Department of Chemistry and Applied Bioscience, Laboratory of Organic Chemistry, Vladimir Prelog Weg 3, 8093, Zurich (Switzerland)
| | - Maxim Yulikov
- ETH Zurich, Department of Chemistry and Applied Bioscience, Laboratory of Physical Chemistry, Vladimir Prelog Weg 2, 8093, Zurich (Switzerland).
| | - Helma Wennemers
- ETH Zurich, Department of Chemistry and Applied Bioscience, Laboratory of Organic Chemistry, Vladimir Prelog Weg 3, 8093, Zurich (Switzerland).
| | - Gunnar Jeschke
- ETH Zurich, Department of Chemistry and Applied Bioscience, Laboratory of Physical Chemistry, Vladimir Prelog Weg 2, 8093, Zurich (Switzerland).
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32
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Schütze F, Krumova M, Mecking S. Size Control of Spherical and Anisotropic Fluorescent Polymer Nanoparticles via Precise Rigid Molecules. Macromolecules 2015. [DOI: 10.1021/acs.macromol.5b00591] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Friederike Schütze
- Chair of Chemical Materials
Science, Department of Chemistry, University of Konstanz, 78464 Konstanz, Germany
| | - Marina Krumova
- Chair of Chemical Materials
Science, Department of Chemistry, University of Konstanz, 78464 Konstanz, Germany
| | - Stefan Mecking
- Chair of Chemical Materials
Science, Department of Chemistry, University of Konstanz, 78464 Konstanz, Germany
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33
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Romano F, Manoni R, Franchi P, Mezzina E, Lucarini M. Supramolecular control of spin exchange in a spin-labelled [2]rotaxane incorporating a tetrathiafulvalene unit. Chemistry 2015; 21:2775-9. [PMID: 25538046 DOI: 10.1002/chem.201406301] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Indexed: 11/07/2022]
Abstract
The EPR properties of a novel triradical obtained by single-electron oxidation of a nitroxide-spin-labelled rotaxane containing a tetrathiafulvalene unit and cyclobis(paraquat-p-phenylene) ring is reported. Rotaxanation is proved to have a dramatic effect on through-space magnetic interactions between radical fragments. Analysis of the EPR spectra by a three-jump model, allowed us to obtain structural information on the interlocked structure.
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Affiliation(s)
- Francesco Romano
- Department of Chemistry "G. Ciamician", University of Bologna, Via S. Giacomo 11, 40126, Bologna (Italy) http://www.ciam.unibo.it/radicals
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34
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Vincent Ching HY, Demay-Drouhard P, Bertrand HC, Policar C, Tabares LC, Un S. Nanometric distance measurements between Mn(ii)DOTA centers. Phys Chem Chem Phys 2015; 17:23368-77. [DOI: 10.1039/c5cp03487f] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The distance between two Mn(ii)DOTA complexes attached to the ends of polyproline helices of varying lengths was measured by 94 GHz PELDOR spectroscopy with good accuracy demonstrating their effectiveness as spin-labels.
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Affiliation(s)
- H. Y. Vincent Ching
- Institute for Integrative Biology of the Cell (I2BC)
- Department of Biochemistry
- Biophysics and Structural Biology
- Université Paris-Saclay
- CEA
| | - Paul Demay-Drouhard
- Ecole Normale Supérieure-PSL Research University
- Départment de Chimie
- Sorbonne Universités – UPMC Univ Paris 06
- CNRS UMR 7203 LBM
- F-75005 Paris
| | - Hélène C. Bertrand
- Ecole Normale Supérieure-PSL Research University
- Départment de Chimie
- Sorbonne Universités – UPMC Univ Paris 06
- CNRS UMR 7203 LBM
- F-75005 Paris
| | - Clotilde Policar
- Ecole Normale Supérieure-PSL Research University
- Départment de Chimie
- Sorbonne Universités – UPMC Univ Paris 06
- CNRS UMR 7203 LBM
- F-75005 Paris
| | - Leandro C. Tabares
- Institute for Integrative Biology of the Cell (I2BC)
- Department of Biochemistry
- Biophysics and Structural Biology
- Université Paris-Saclay
- CEA
| | - Sun Un
- Institute for Integrative Biology of the Cell (I2BC)
- Department of Biochemistry
- Biophysics and Structural Biology
- Université Paris-Saclay
- CEA
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35
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Dalaloyan A, Qi M, Ruthstein S, Vega S, Godt A, Feintuch A, Goldfarb D. Gd(iii)–Gd(iii) EPR distance measurements – the range of accessible distances and the impact of zero field splitting. Phys Chem Chem Phys 2015; 17:18464-76. [DOI: 10.1039/c5cp02602d] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Gd rulers were designed in the 2–8 nm range for in-depth evaluation of Gd(iii) complexes as spin labels for EPR distance measurements.
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Affiliation(s)
- Arina Dalaloyan
- Department of Chemical Physics
- Weizmann Institute of Science
- Rehovot
- Israel
| | - Mian Qi
- Bielefeld University
- Faculty of Chemistry and Center for Molecular Materials
- D-33615 Bielefeld
- Germany
| | - Sharon Ruthstein
- Department of Chemistry
- Faculty of Exact Sciences
- Bar-Ilan University
- Ramat Gan
- Israel
| | - Shimon Vega
- Department of Chemical Physics
- Weizmann Institute of Science
- Rehovot
- Israel
| | - Adelheid Godt
- Bielefeld University
- Faculty of Chemistry and Center for Molecular Materials
- D-33615 Bielefeld
- Germany
| | - Akiva Feintuch
- Department of Chemical Physics
- Weizmann Institute of Science
- Rehovot
- Israel
| | - Daniella Goldfarb
- Department of Chemical Physics
- Weizmann Institute of Science
- Rehovot
- Israel
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36
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Hintze C, Schütze F, Drescher M, Mecking S. Probing of chain conformations in conjugated polymer nanoparticles by electron spin resonance spectroscopy. Phys Chem Chem Phys 2015; 17:32289-96. [DOI: 10.1039/c5cp05749c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Direct observation of individual conjugated polymer chain conformations in nanoparticles by ESR distance measurements.
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Affiliation(s)
- C. Hintze
- Department of Chemistry
- University of Konstanz
- 78464 Konstanz
- Germany
| | - F. Schütze
- Department of Chemistry
- University of Konstanz
- 78464 Konstanz
- Germany
| | - M. Drescher
- Department of Chemistry
- University of Konstanz
- 78464 Konstanz
- Germany
| | - S. Mecking
- Department of Chemistry
- University of Konstanz
- 78464 Konstanz
- Germany
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37
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Combining NMR and EPR to Determine Structures of Large RNAs and Protein–RNA Complexes in Solution. Methods Enzymol 2015; 558:279-331. [DOI: 10.1016/bs.mie.2015.02.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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38
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39
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Doll A, Qi M, Pribitzer S, Wili N, Yulikov M, Godt A, Jeschke G. Sensitivity enhancement by population transfer in Gd(iii) spin labels. Phys Chem Chem Phys 2015; 17:7334-44. [DOI: 10.1039/c4cp05893c] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Frequency-swept chirp pulses with bandwidths > 1 GHz rearrange electron spin populations in the S = 7/2 spin of Gd(iii) ions for better sensitivity, as demonstrated with distance measurements between Gd(iii) ions.
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Affiliation(s)
- Andrin Doll
- Laboratory of Physical Chemistry
- ETH Zurich
- 8093 Zurich
- Switzerland
| | - Mian Qi
- Faculty of Chemistry and Center for Molecular Materials
- Bielefeld University
- 33615 Bielefeld
- Germany
| | | | - Nino Wili
- Laboratory of Physical Chemistry
- ETH Zurich
- 8093 Zurich
- Switzerland
| | - Maxim Yulikov
- Laboratory of Physical Chemistry
- ETH Zurich
- 8093 Zurich
- Switzerland
| | - Adelheid Godt
- Faculty of Chemistry and Center for Molecular Materials
- Bielefeld University
- 33615 Bielefeld
- Germany
| | - Gunnar Jeschke
- Laboratory of Physical Chemistry
- ETH Zurich
- 8093 Zurich
- Switzerland
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40
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Abdullin D, Florin N, Hagelueken G, Schiemann O. EPR-based approach for the localization of paramagnetic metal ions in biomolecules. Angew Chem Int Ed Engl 2014; 54:1827-31. [PMID: 25522037 DOI: 10.1002/anie.201410396] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Indexed: 11/10/2022]
Abstract
Metal ions play an important role in the catalysis and folding of proteins and oligonucleotides. Their localization within the three-dimensional fold of such biomolecules is therefore an important goal in understanding structure-function relationships. A trilateration approach for the localization of metal ions by means of long-range distance measurements based on electron paramagnetic resonance (EPR) is introduced. The approach is tested on the Cu(2+) center of azurin, and factors affecting the precision of the method are discussed.
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Affiliation(s)
- Dinar Abdullin
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstrasse 12, 53115 Bonn (Germany) http://www.schiemann.uni-bonn.de
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41
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Abdullin D, Florin N, Hagelueken G, Schiemann O. EPR-Based Approach for the Localization of Paramagnetic Metal Ions in Biomolecules. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201410396] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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42
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Valera S, Bode BE. Strategies for the synthesis of yardsticks and abaci for nanometre distance measurements by pulsed EPR. Molecules 2014; 19:20227-56. [PMID: 25479188 PMCID: PMC6271543 DOI: 10.3390/molecules191220227] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 11/19/2014] [Accepted: 11/27/2014] [Indexed: 01/18/2023] Open
Abstract
Pulsed electron paramagnetic resonance (EPR) techniques have been found to be efficient tools for the elucidation of structure in complex biological systems as they give access to distances in the nanometre range. These measurements can provide additional structural information such as relative orientations, structural flexibility or aggregation states. A wide variety of model systems for calibration and optimisation of pulsed experiments has been synthesised. Their design is based on mimicking biological systems or materials in specific properties such as the distances themselves and the distance distributions. Here, we review selected approaches to the synthesis of chemical systems bearing two or more spin centres, such as nitroxide or trityl radicals, metal ions or combinations thereof and outline their application in pulsed EPR distance measurements.
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Affiliation(s)
- Silvia Valera
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic Resonance, University of St Andrews, KY16 9ST Fife, UK
| | - Bela E Bode
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic Resonance, University of St Andrews, KY16 9ST Fife, UK.
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43
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Qi M, Groß A, Jeschke G, Godt A, Drescher M. Gd(III)-PyMTA Label Is Suitable for In-Cell EPR. J Am Chem Soc 2014; 136:15366-78. [DOI: 10.1021/ja508274d] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Mian Qi
- Faculty
of Chemistry and Center for Molecular Materials, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Andreas Groß
- Department
of Chemistry, Zukunftskolleg, and Konstanz Research School Chemical
Biology, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Gunnar Jeschke
- Laboratory
of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Adelheid Godt
- Faculty
of Chemistry and Center for Molecular Materials, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Malte Drescher
- Department
of Chemistry, Zukunftskolleg, and Konstanz Research School Chemical
Biology, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
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44
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Abdullin D, Hagelueken G, Hunter RI, Smith GM, Schiemann O. Geometric model-based fitting algorithm for orientation-selective PELDOR data. Mol Phys 2014. [DOI: 10.1080/00268976.2014.960494] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Dinar Abdullin
- Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn, Germany
| | - Gregor Hagelueken
- Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn, Germany
| | | | | | - Olav Schiemann
- Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn, Germany
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45
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Valera S, Taylor JE, Daniels DSB, Dawson DM, Athukorala Arachchige KS, Ashbrook SE, Slawin AMZ, Bode BE. A modular approach for the synthesis of nanometer-sized polynitroxide multi-spin systems. J Org Chem 2014; 79:8313-23. [PMID: 25102422 DOI: 10.1021/jo5015678] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The synthesis of rigid symmetric polyradical model systems with inter-spin distances between 1.4 and 4 nm and their room temperature continuous wave (CW) EPR spectra are reported. Conditions for attachment of the spin-label via esterification have been optimized on the direct synthesis of polyradicals from commercially available polyphenols and the carboxylic acid functionalized nitroxide TPC. A common synthetic protocol utilizing 4-hydroxy-4'-iodobiphenyl as a key building block has been used to synthesize an equilateral biradical and a triradical in only two steps from commercially available starting materials. The first synthesis of a tetraradical based upon an adamantane core bearing six equivalent nitroxide-nitroxide distances is also reported. These systems are very promising candidates for studying multi-spin effects in pulsed EPR distance measurements.
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Affiliation(s)
- Silvia Valera
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic Resonance, University of St Andrews , North Haugh, St Andrews KY16 9ST, United Kingdom
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Ji M, Ruthstein S, Saxena S. Paramagnetic metal ions in pulsed ESR distance distribution measurements. Acc Chem Res 2014; 47:688-95. [PMID: 24289139 DOI: 10.1021/ar400245z] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The use of pulsed electron spin resonance (ESR) to measure interspin distance distributions has advanced biophysical research. The three major techniques that use pulsed ESR are relaxation rate based distance measurements, double quantum coherence (DQC), and double electron electron resonance (DEER). Among these methods, the DEER technique has become particularly popular largely because it is easy to implement on commercial instruments and because programs are available to analyze experimental data. Researchers have widely used DEER to measure the structure and conformational dynamics of molecules labeled with the methanethiosulfonate spin label (MTSSL). Recently, researchers have exploited endogenously bound paramagnetic metal ions as spin probes as a way to determine structural constraints in metalloproteins. In this context Cu(2+) has served as a useful paramagnetic metal probe at X-band for DEER based distance measurements. Sample preparation is simple, and a coordinated-Cu(2+) ion offers limited spatial flexibility, making it an attractive probe for DEER experiments. On the other hand, Cu(2+) has a broad absorption ESR spectrum at low temperature, which leads to two potential complications. First, the Cu(2+)-based DEER time domain data has lower signal to noise ratio compared with MTSSL. Second, accurate distance distribution analysis often requires high-quality experimental data at different external magnetic fields or with different frequency offsets. In this Account, we summarize characteristics of Cu(2+)-based DEER distance distribution measurements and data analysis methods. We highlight a novel application of such measurements in a protein-DNA complex to identify the metal ion binding site and to elucidate its chemical mechanism of function. We also survey the progress of research on other metal ions in high frequency DEER experiments.
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Affiliation(s)
- Ming Ji
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Sharon Ruthstein
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Chemistry, Faculty of Exact Science, Bar Ilan University, Ramat-Gan 5290002, Israel
| | - Sunil Saxena
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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Pochorovski I, Knehans T, Nettels D, Müller AM, Schweizer WB, Caflisch A, Schuler B, Diederich F. Experimental and computational study of BODIPY dye-labeled cavitand dynamics. J Am Chem Soc 2014; 136:2441-9. [PMID: 24490940 DOI: 10.1021/ja4104292] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Understanding the distance distribution and dynamics between moieties attached to the walls of a resorcin[4]arene cavitand, which is switchable between an expanded kite and a contracted vase form, might enable the use of this molecular system for the study of fundamental distance-dependent interactions. Toward this goal, a combined experimental and molecular dynamics (MD) simulation study on donor/acceptor borondipyrromethene (BODIPY) dye-labeled cavitands present in the vase and kite forms was performed. Direct comparison between anisotropy decays calculated from MD simulations with experimental fluorescence anisotropy data showed excellent agreement, indicating that the simulations provide an accurate representation of the dynamics of the system. Distance distributions between the BODIPY dyes were established by comparing time-resolved Förster resonance energy transfer experiments and MD simulations. Fluorescence intensity decay curves emulated on the basis of the MD trajectories showed good agreement with the experimental data, suggesting that the simulations present an accurate picture of the distance distributions and dynamics in this molecular system and provide an important tool for understanding the behavior of extended molecular systems and designing future applications.
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Affiliation(s)
- Igor Pochorovski
- Laboratorium für Organische Chemie, ETH Zürich , Hönggerberg, HCI, 8093 Zürich, Switzerland
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Kunjir NC, Reginsson GW, Schiemann O, Sigurdsson ST. Measurements of short distances between trityl spin labels with CW EPR, DQC and PELDOR. Phys Chem Chem Phys 2013; 15:19673-85. [PMID: 24135783 DOI: 10.1039/c3cp52789a] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Trityl based spin labels are emerging as a complement to nitroxides in nanometer distance measurements using EPR methods. The narrow spectral width of the trityl radicals prompts us to ask the question at which distance between these spin centers, the pseudo-secular part of the dipolar coupling and spin density delocalization have to be taken into account. For this, two trityl-trityl and one trityl-nitroxide model compounds were synthesized with well-defined interspin distances. Continuous wave (CW) EPR, double quantum coherence (DQC) and pulsed electron-electron double resonance (PELDOR) spectra were acquired from these compounds at commercial X-band frequencies. The data analysis shows that two of the compounds, with distances of up to 25 Å, fall into the strong coupling regime and that precise distances can only be obtained if both the spin density delocalization and the pseudo-secular part of the dipolar coupling are included in the analysis.
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Affiliation(s)
- Nitin C Kunjir
- University of Iceland, Department of Chemistry, Science Institute, Dunhaga 3, 107 Reykjavík, Iceland.
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Tsvetkov YD. Nitroxyls and PELDOR: Nitroxyl radicals in pulsed electron-electron double resonance spectroscopy. J STRUCT CHEM+ 2013. [DOI: 10.1134/s0022476613070044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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50
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Milov AD, Tsvetkov YD, De Zotti M, Prinzivalli C, Biondi B, Formaggio F, Toniolo C, Gobbo M. Aggregation modes of the spin mono-labeled tylopeptin B and heptaibin peptaibiotics in frozen solutions of weak polarity as studied by PELDOR spectroscopy. J STRUCT CHEM+ 2013. [DOI: 10.1134/s0022476613070056] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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