1
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Mena A, Mann SK, Cowley-Semple A, Bryan E, Heutz S, McCamey DR, Attwood M, Bayliss SL. Room-Temperature Optically Detected Coherent Control of Molecular Spins. PHYSICAL REVIEW LETTERS 2024; 133:120801. [PMID: 39373412 DOI: 10.1103/physrevlett.133.120801] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Accepted: 08/13/2024] [Indexed: 10/08/2024]
Abstract
Optically interfaced molecular spins are a promising platform for quantum sensing and imaging. Key for such applications is optically detecting coherent spin manipulation at room temperature. Here, using the photoexcited triplet state of organic chromophores (pentacene doped in p-terphenyl), we optically detect coherent spin manipulation with photoluminescence contrasts exceeding 15% at room temperature, both in a molecular crystal and thin film. We further demonstrate how multifrequency spin control could enhance such systems. These results open opportunities for room-temperature quantum sensors that capitalize on the versatility of synthetic chemistry.
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Affiliation(s)
- Adrian Mena
- James Watt School of Engineering, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
- ARC Centre of Excellence in Exciton Science, School of Physics, UNSW Sydney, Sydney, 2052, New South Wales, Australia
| | | | | | | | | | - Dane R McCamey
- ARC Centre of Excellence in Exciton Science, School of Physics, UNSW Sydney, Sydney, 2052, New South Wales, Australia
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2
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Bertran A, De Zotti M, Timmel CR, Di Valentin M, Bowen AM. Determining and controlling conformational information from orientationally selective light-induced triplet-triplet electron resonance spectroscopy for a set of bis-porphyrin rulers. Phys Chem Chem Phys 2024; 26:2589-2602. [PMID: 38170870 PMCID: PMC10793979 DOI: 10.1039/d3cp03454b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 10/31/2023] [Indexed: 01/05/2024]
Abstract
We recently reported a new technique, light-induced triplet-triplet electron resonance (LITTER) spectroscopy, which allows quantification of the dipolar interaction between the photogenerated triplet states of two chromophores. Here we carry out a systematic LITTER study, considering orientation selection by the detection pulses, of a series of bis-porphyrin model peptides with different porphyrin-porphyrin distances and relative orientations. Orientation-dependent analysis of the dipolar datasets yields conformational information of the molecules in frozen solution which is in good agreement with density functional theory predictions. Additionally, a fast partial orientational-averaging treatment produces distance distributions with minimized orientational artefacts. Finally, by direct comparison of LITTER data to double electron-electron resonance (DEER) measured on a system with Cu(II) coordinated into the porphyrins, we demonstrate the advantages of the LITTER technique over the standard DEER methodology. This is due to the remarkable spectroscopic properties of the photogenerated porphyrin triplet state. This work sets the basis for the use of LITTER in structural investigations of unmodified complex biological macromolecules, which could be combined with Förster resonance energy transfer and microscopy inside cells.
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Affiliation(s)
- Arnau Bertran
- Centre for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, UK.
| | - Marta De Zotti
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
- Centro Interdipartimentale di Ricerca "Centro Studi di Economia e Tecnica dell'energia Giorgio Levi Cases", 35131 Padova, Italy.
| | - Christiane R Timmel
- Centre for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, UK.
| | - Marilena Di Valentin
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
- Centro Interdipartimentale di Ricerca "Centro Studi di Economia e Tecnica dell'energia Giorgio Levi Cases", 35131 Padova, Italy.
| | - Alice M Bowen
- The National Research Facility for Electron Paramagnetic Resonance, Department of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, UK.
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3
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Bertran A, Morbiato L, Sawyer J, Dalla Torre C, Heyes DJ, Hay S, Timmel CR, Di Valentin M, De Zotti M, Bowen AM. Direct Comparison between Förster Resonance Energy Transfer and Light-Induced Triplet-Triplet Electron Resonance Spectroscopy. J Am Chem Soc 2023; 145:22859-22865. [PMID: 37839071 PMCID: PMC10603778 DOI: 10.1021/jacs.3c04685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Indexed: 10/17/2023]
Abstract
To carry out reliable and comprehensive structural investigations, the exploitation of different complementary techniques is required. Here, we report that dual triplet-spin/fluorescent labels enable the first parallel distance measurements by electron spin resonance (ESR) and Förster resonance energy transfer (FRET) on exactly the same molecules with orthogonal chromophores, allowing for direct comparison. An improved light-induced triplet-triplet electron resonance method with 2-color excitation is used, improving the signal-to-noise ratio of the data and yielding a distance distribution that provides greater insight than the single distance resulting from FRET.
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Affiliation(s)
- Arnau Bertran
- Centre
for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory,
Department of Chemistry, University of Oxford, Oxford OX1 3QR, United Kingdom
| | - Laura Morbiato
- Department
of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Jack Sawyer
- The
National Research Facility for Electron Paramagnetic Resonance, Department
of Chemistry, Manchester Institute of Biotechnology and Photon Science
Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Chiara Dalla Torre
- Department
of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Derren J. Heyes
- The
National Research Facility for Electron Paramagnetic Resonance, Department
of Chemistry, Manchester Institute of Biotechnology and Photon Science
Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Sam Hay
- The
National Research Facility for Electron Paramagnetic Resonance, Department
of Chemistry, Manchester Institute of Biotechnology and Photon Science
Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Christiane R. Timmel
- Centre
for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory,
Department of Chemistry, University of Oxford, Oxford OX1 3QR, United Kingdom
| | - Marilena Di Valentin
- Department
of Chemical Sciences, University of Padova, 35131 Padova, Italy
- Centro
Interdipartimentale di Ricerca “Centro Studi di Economia e
Tecnica dell’energia Giorgio Levi Cases”, 35131 Padova, Italy
| | - Marta De Zotti
- Department
of Chemical Sciences, University of Padova, 35131 Padova, Italy
- Centro
Interdipartimentale di Ricerca “Centro Studi di Economia e
Tecnica dell’energia Giorgio Levi Cases”, 35131 Padova, Italy
| | - Alice M. Bowen
- The
National Research Facility for Electron Paramagnetic Resonance, Department
of Chemistry, Manchester Institute of Biotechnology and Photon Science
Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
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4
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Sannikova NE, Kolokolov MI, Khlynova TA, Chubarov AS, Polienko YF, Fedin MV, Krumkacheva OA. Revealing light-induced structural shifts in G-quadruplex-porphyrin complexes: a pulsed dipolar EPR study. Phys Chem Chem Phys 2023; 25:22455-22466. [PMID: 37581249 DOI: 10.1039/d3cp01775c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
The binding of G-quadruplex structures (G4s) with photosensitizers is of considerable importance in medicinal chemistry and drug discovery due to their promising potential in photodynamic therapy applications. G4s can experience structural changes as a result of ligand interactions and light exposure. Understanding these modifications is essential to uncover the fundamental biological roles of the complexes and optimize their therapeutic potential. The structural diversity of G4s makes it challenging to study their complexes with ligands, necessitating the use of various complementary methods to fully understand these interactions. In this study, we introduce, for the first time, the application of laser-induced dipolar EPR as a method to characterize G-quadruplex DNA complexes containing photosensitizers and to investigate light-induced structural modifications in these systems. To demonstrate the feasibility of this approach, we studied complexes of the human telomeric G-quadruplex (HTel-22) with cationic 5,10,15,20-tetrakis(1-methyl-4-pyridinio) porphyrin tetra(p-toluenesulfonate) (TMPyP4). In addition to showcasing a new methodology, we also aimed to provide insights into the mechanisms underlying photoinduced HTel-22/TMPyP4 structural changes, thereby aiding in the advancement of approaches targeting G4s in photodynamic therapy. EPR revealed G-quadruplex unfolding and dimer formation upon light exposure. Our findings demonstrate the potential of EPR spectroscopy for examining G4 complexes with photosensitizers and contribute to a better understanding of G4s' interactions with ligands under light.
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Affiliation(s)
- Natalya E Sannikova
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia.
- Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia
| | - Mikhail I Kolokolov
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia.
- Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia
| | - Tamara A Khlynova
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia.
- Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia
| | - Alexey S Chubarov
- Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk 630090, Russia
- Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia
| | - Yuliya F Polienko
- N.N. Vorozhtsov Institute of Organic Chemistry SB RAS, 630090 Novosibirsk, Russia
| | - Matvey V Fedin
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia.
- Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia
| | - Olesya A Krumkacheva
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia.
- Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia
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5
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Tait CE, Krzyaniak MD, Stoll S. Computational tools for the simulation and analysis of spin-polarized EPR spectra. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 349:107410. [PMID: 36870248 DOI: 10.1016/j.jmr.2023.107410] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/10/2023] [Accepted: 02/18/2023] [Indexed: 06/18/2023]
Abstract
The EPR spectra of paramagnetic species induced by photoexcitation typically exhibit enhanced absorptive and emissive features resulting from sublevel populations that differ from thermal equilibrium. The populations and the resulting spin polarization of the spectra are dictated by the selectivity of the photophysical process generating the observed state. Simulation of the spin-polarized EPR spectra is crucial in the characterization of both the dynamics of formation of the photoexcited state as well as its electronic and structural properties. EasySpin, the simulation toolbox for EPR spectroscopy, now includes extended support for the simulation of the EPR spectra of spin-polarized states of arbitrary spin multiplicity and formed by a variety of different mechanisms, including photoexcited triplet states populated by intersystem crossing, charge recombination or spin polarization transfer, spin-correlated radical pairs created by photoinduced electron transfer, triplet pairs formed by singlet fission and multiplet states arising from photoexcitation in systems containing chromophores and stable radicals. In this paper, we highlight EasySpin's capabilities for the simulation of spin-polarized EPR spectra on the basis of illustrative examples from the literature in a variety of fields ranging across chemistry, biology, material science and quantum information science.
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Affiliation(s)
- Claudia E Tait
- Department of Chemistry, University of Oxford, Oxford OX1 3QZ, United Kingdom.
| | - Matthew D Krzyaniak
- Department of Chemistry, Center for Molecular Quantum Transduction and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston 60208, IL, United States
| | - Stefan Stoll
- Department of Chemistry, University of Washington, Seattle, 98195, WA, United States
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6
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Scherer A, Yildirim B, Drescher M. The effect of the zero-field splitting in light-induced pulsed dipolar electron paramagnetic resonance (EPR) spectroscopy. MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2023; 4:27-46. [PMID: 37904801 PMCID: PMC10583298 DOI: 10.5194/mr-4-27-2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 01/13/2023] [Indexed: 11/01/2023]
Abstract
Laser-induced magnetic dipole (LaserIMD) spectroscopy and light-induced double electron-electron resonance (LiDEER) spectroscopy are important techniques in the emerging field of light-induced pulsed dipolar electron paramagnetic resonance (EPR) spectroscopy (light-induced PDS). These techniques use the photoexcitation of a chromophore to the triplet state and measure its dipolar coupling to a neighboring electron spin, which allows the determination of distance restraints. To date, LaserIMD and LiDEER have been analyzed with software tools that were developed for a pair of two S = 1 / 2 spins and that neglected the zero-field splitting (ZFS) of the excited triplet. Here, we explore the limits of this assumption and show that the ZFS can have a significant effect on the shape of the dipolar trace. For a detailed understanding of the effect of the ZFS, a theoretical description for LaserIMD and LiDEER is derived, taking into account the non-secular terms of the ZFS. Simulations based on this model show that the effect of the ZFS is not that pronounced in LiDEER for experimentally relevant conditions. However, the ZFS leads to an additional decay in the dipolar trace in LaserIMD. This decay is not that pronounced in Q-band but can be quite noticeable for lower magnetic field strengths in X-band. Experimentally recorded LiDEER and LaserIMD data confirm these findings. It is shown that ignoring the ZFS in the data analysis of LaserIMD traces can lead to errors in the obtained modulation depths and background decays. In X-band, it is additionally possible that the obtained distance distribution is plagued by long distance artifacts.
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Affiliation(s)
- Andreas Scherer
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Berk Yildirim
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Malte Drescher
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, 78457 Konstanz, Germany
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7
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Scherer A, Yao X, Qi M, Wiedmaier M, Godt A, Drescher M. Increasing the Modulation Depth of Gd III-Based Pulsed Dipolar EPR Spectroscopy (PDS) with Porphyrin-Gd III Laser-Induced Magnetic Dipole Spectroscopy. J Phys Chem Lett 2022; 13:10958-10964. [PMID: 36399541 PMCID: PMC9720741 DOI: 10.1021/acs.jpclett.2c02138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 10/03/2022] [Indexed: 06/16/2023]
Abstract
Distance determination with pulsed EPR has become an important technique for the structural investigation of biomacromolecules, with double electron-electron resonance spectroscopy (DEER) as the most important method. GdIII-based spin labels are one of the most frequently used spin labels for DEER owing to their stability against reduction, high magnetic moment, and absence of orientation selection. A disadvantage of GdIII-GdIII DEER is the low modulation depth due to the broad EPR spectrum of GdIII. Here, we introduce laser-induced magnetic dipole spectroscopy (LaserIMD) with a spin pair consisting of GdIII(PymiMTA) and a photoexcited porphyrin as an alternative technique. We show that the excited state of the porphyrin is not disturbed by the presence of the GdIII complex and that herewith modulation depths of almost 40% are possible. This is significantly higher than the value of 7.2% that was achieved with GdIII-GdIII DEER.
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Affiliation(s)
- Andreas Scherer
- Department
of Chemistry and Konstanz Research School Chemical Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Xuemei Yao
- Faculty
of Chemistry and Center of Molecular Materials (CM2), Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Mian Qi
- Faculty
of Chemistry and Center of Molecular Materials (CM2), Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Max Wiedmaier
- Department
of Chemistry and Konstanz Research School Chemical Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Adelheid Godt
- Faculty
of Chemistry and Center of Molecular Materials (CM2), Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Malte Drescher
- Department
of Chemistry and Konstanz Research School Chemical Biology, University of Konstanz, 78457 Konstanz, Germany
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8
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Bertran A, Morbiato L, Aquilia S, Gabbatore L, De Zotti M, Timmel CR, Di Valentin M, Bowen AM. Erythrosin B as a New Photoswitchable Spin Label for Light-Induced Pulsed EPR Dipolar Spectroscopy. Molecules 2022; 27:molecules27217526. [PMID: 36364348 PMCID: PMC9657417 DOI: 10.3390/molecules27217526] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 10/27/2022] [Accepted: 10/29/2022] [Indexed: 11/06/2022] Open
Abstract
We present a new photoswitchable spin label for light-induced pulsed electron paramagnetic resonance dipolar spectroscopy (LiPDS), the photoexcited triplet state of erythrosin B (EB), which is ideal for biological applications. With this label, we perform an in-depth study of the orientational effects in dipolar traces acquired using the refocused laser-induced magnetic dipole technique to obtain information on the distance and relative orientation between the EB and nitroxide labels in a rigid model peptide, in good agreement with density functional theory predictions. Additionally, we show that these orientational effects can be averaged to enable an orientation-independent analysis to determine the distance distribution. Furthermore, we demonstrate the feasibility of these experiments above liquid nitrogen temperatures, removing the need for expensive liquid helium or cryogen-free cryostats. The variety of choices in photoswitchable spin labels and the affordability of the experiments are critical for LiPDS to become a widespread methodology in structural biology.
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Affiliation(s)
- Arnau Bertran
- Centre for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QR, UK
| | - Laura Morbiato
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Sara Aquilia
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Laura Gabbatore
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Marta De Zotti
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy
- Centro Interdipartimentale di Ricerca “Centro Studi di Economia e Tecnica dell’Energia Giorgio Levi Cases”, University of Padova, 35131 Padova, Italy
| | - Christiane R. Timmel
- Centre for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QR, UK
| | - Marilena Di Valentin
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy
- Centro Interdipartimentale di Ricerca “Centro Studi di Economia e Tecnica dell’Energia Giorgio Levi Cases”, University of Padova, 35131 Padova, Italy
- Correspondence: (M.D.V.); (A.M.B.)
| | - Alice M. Bowen
- The National Research Facility for Electron Paramagnetic Resonance, Department of Chemistry and Photon Science Institute, The University of Manchester, Manchester M13 9PL, UK
- Correspondence: (M.D.V.); (A.M.B.)
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9
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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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10
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Al Said T, Weber S, Schleicher E. OOP-ESEEM Spectroscopy: Accuracies of Distances of Spin-Correlated Radical Pairs in Biomolecules. Front Mol Biosci 2022; 9:890826. [PMID: 35813811 PMCID: PMC9262093 DOI: 10.3389/fmolb.2022.890826] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Accepted: 05/05/2022] [Indexed: 11/30/2022] Open
Abstract
In addition to the commonly used electron-electron double resonance (ELDOR) technique, there are several other electron paramagnetic resonance (EPR) methods by which structure information can be obtained by exploiting the dipolar coupling between two radicals based on its characteristic r -3 dependence. In this contribution, we explore the potential of out-of-phase-electron-spin echo envelope modulation (OOP-ESEEM) spectroscopy to collect accurate distance information in photo-sensitive (bio) molecules. Although the method has already been applied to spin-correlated radical pairs in several classes of light-active proteins, the accuracy of the information obtained has not yet been extensively evaluated. To do this in a system-independent fashion, OOP-ESEEM time traces simulated with different values of the dipolar and exchange couplings were generated and analyzed in a best-possible way. Excellent agreement between calculated and numerically fitted values over a wide range of distances (between 15 and 45 Å) was obtained. Furthermore, the limitations of the method and the dependence on various experimental parameters could be evaluated.
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Affiliation(s)
| | | | - Erik Schleicher
- Institute of Physical Chemistry, University of Freiburg, Freiburg, Germany
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11
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Fábregas-Ibáñez L, Jeschke G, Stoll S. Compactness regularization in the analysis of dipolar EPR spectroscopy data. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 339:107218. [PMID: 35439683 DOI: 10.1016/j.jmr.2022.107218] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 04/04/2022] [Accepted: 04/05/2022] [Indexed: 06/14/2023]
Abstract
Dipolar electron paramagnetic resonance (EPR) experiments, such as double electron-electron resonance (DEER), measure distributions of nanometer-scale distances between paramagnetic centers, which are valuable for structural characterization of proteins and other macromolecular systems. One challenge in the least-squares fitting analysis of dipolar EPR data is the separation of the inter-molecular contribution (background) and the intra-molecular contribution. For noisy experimental traces of insufficient length, this separation is not unique, leading to identifiability problems for the background model parameters and the long-distance region of the intra-molecular distance distribution. Here, we introduce a regularization approach that mitigates this by including an additional penalty term in the objective function that is proportional to the variance of the distance distribution and thereby penalizes non-compact distributions. We examine the reliability of this approach statistically on a large set of synthetic data and illustrate it with an experimental example. The results show that the introduction of compactness can improve identifiability.
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Affiliation(s)
- Luis Fábregas-Ibáñez
- ETH Zurich, Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, Zurich 8093, Switzerland.
| | - Gunnar Jeschke
- ETH Zurich, Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, Zurich 8093, Switzerland
| | - Stefan Stoll
- University of Washington, Department of Chemistry, Seattle, WA 98195, USA
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12
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Abstract
Different types of spin labels are currently available for structural studies of biomolecules both in vitro and in cells using Electron Paramagnetic Resonance (EPR) and pulse dipolar spectroscopy (PDS). Each type of label has its own advantages and disadvantages, that will be addressed in this chapter. The spectroscopically distinct properties of the labels have fostered new applications of PDS aimed to simultaneously extract multiple inter-label distances on the same sample. In fact, combining different labels and choosing the optimal strategy to address their inter-label distances can increase the information content per sample, and this is pivotal to better characterize complex multi-component biomolecular systems. In this review, we provide a brief background of the spectroscopic properties of the four most common orthogonal spin labels for PDS measurements and focus on the various methods at disposal to extract homo- and hetero-label distances in proteins. We also devote a section to possible artifacts arising from channel crosstalk and provide few examples of applications in structural biology.
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13
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Bertran A, Barbon A, Bowen AM, Di Valentin M. Light-induced pulsed dipolar EPR spectroscopy for distance and orientation analysis. Methods Enzymol 2022; 666:171-231. [PMID: 35465920 DOI: 10.1016/bs.mie.2022.02.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Measuring distances in biology at the molecular level is of great importance for understanding the structure and function of proteins, nucleic acids and other biological molecules and their complexes. Pulsed Dipolar Spectroscopy (PDS) offers advantages with respect to other methods as it is uniquely sensitive and specific to electronic spin centers and allows measurements in near-native conditions, comprising the in-cell environment. PDS methods measure the electron spin-spin dipolar interaction, therefore they require the presence of at least two paramagnetic centers, which are often stable radicals. Recent developments have introduced transient triplet states, photo-activated by a laser pulse, as spin labels and probes, thereby establishing a new family of techniques-Light-induced PDS (LiPDS). In this chapter, an overview of these methods is provided, looking at the chromophores that can be used for LiPDS and some of the technical aspects of the experiments. A guide to the choice of technique that can yield the best results, depending on the type of system studied and the information required, is provided. Examples of previous LiPDS studies of model systems and proteins are given. Characterization data for the chromophores used in these studies is tabulated to help selection of appropriate triplet state probes in future studies.
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Affiliation(s)
- Arnau Bertran
- Centre for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | - Antonio Barbon
- Department of Chemical Sciences, University of Padova, Padova, Italy
| | - Alice M Bowen
- Centre for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, United Kingdom; EPSRC National Research Facility for Electron Paramagnetic Resonance Spectroscopy, Department of Chemistry and Photon Science Institute, The University of Manchester, Manchester, United Kingdom.
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14
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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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15
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Timofeev IO, Politanskaya LV, Tretyakov EV, Polienko YF, Tormyshev VM, Bagryanskaya E, Krumkacheva OA, Fedin MV. Fullerene-based triplet spin labels: methodology aspects for pulsed dipolar EPR spectroscopy. Phys Chem Chem Phys 2022; 24:4475-4484. [DOI: 10.1039/d1cp05545c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Triplet states of photoexcited organic molecules are promising spin labels with advanced spectroscopic properties for Pulsed Dipolar Electron Paramagnetic Resonance (PD EPR) spectroscopy. Recently proposed triplet fullerene labels have shown...
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16
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Bowen AM, Bertran A, Henbest KB, Gobbo M, Timmel CR, Di Valentin M. Orientation-Selective and Frequency-Correlated Light-Induced Pulsed Dipolar Spectroscopy. J Phys Chem Lett 2021; 12:3819-3826. [PMID: 33856805 PMCID: PMC8154851 DOI: 10.1021/acs.jpclett.1c00595] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 03/31/2021] [Indexed: 06/12/2023]
Abstract
We explore the potential of orientation-resolved pulsed dipolar spectroscopy (PDS) in light-induced versions of the experiment. The use of triplets as spin-active moieties for PDS offers an attractive tool for studying biochemical systems containing optically active cofactors. Cofactors are often rigidly bound within the protein structure, providing an accurate positional marker. The rigidity leads to orientation selection effects in PDS, which can be analyzed to give both distance and mutual orientation information. Herein we present a comprehensive analysis of the orientation selection of a full set of light-induced PDS experiments. We exploit the complementary information provided by the different light-induced techniques to yield atomic-level structural information. For the first time, we measure a 2D frequency-correlated laser-induced magnetic dipolar spectrum, and we are able to monitor the complete orientation dependence of the system in a single experiment. Alternatively, the summed spectrum enables an orientation-independent analysis to determine the distance distribution.
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Affiliation(s)
- Alice M. Bowen
- Department
of Chemistry, Photon Science Institute and The National EPR Research
Facility, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- Centre
for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory,
Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Arnau Bertran
- Centre
for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory,
Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Kevin B. Henbest
- Centre
for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory,
Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Marina Gobbo
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Christiane R. Timmel
- Centre
for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory,
Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Marilena Di Valentin
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
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17
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Bertran A, Henbest KB, De Zotti M, Gobbo M, Timmel CR, Di Valentin M, Bowen AM. Light-Induced Triplet-Triplet Electron Resonance Spectroscopy. J Phys Chem Lett 2021; 12:80-85. [PMID: 33306382 PMCID: PMC8016185 DOI: 10.1021/acs.jpclett.0c02884] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 11/19/2020] [Indexed: 06/12/2023]
Abstract
We present a new technique, light-induced triplet-triplet electron resonance spectroscopy (LITTER), which measures the dipolar interaction between two photoexcited triplet states, enabling both the distance and angular distributions between the two triplet moieties to be determined on a nanometer scale. This is demonstrated for a model bis-porphyrin peptide that renders dipolar traces with strong orientation selection effects. Using simulations and density functional theory calculations, we extract distance distributions and relative orientations of the porphyrin moieties, allowing the dominant conformation of the peptide in a frozen solution to be identified. LITTER removes the requirement of current light-induced electron spin resonance pulse dipolar spectroscopy techniques to have a permanent paramagnetic moiety, becoming more suitable for in-cell applications and facilitating access to distance determination in unmodified macromolecular systems containing photoexcitable moieties. LITTER also has the potential to enable direct comparison with Förster resonance energy transfer and combination with microscopy inside cells.
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Affiliation(s)
- Arnau Bertran
- Centre
for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory,
Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Kevin B. Henbest
- Centre
for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory,
Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Marta De Zotti
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Marina Gobbo
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Christiane R. Timmel
- Centre
for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory,
Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Marilena Di Valentin
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Alice M. Bowen
- Centre
for Advanced Electron Spin Resonance and Inorganic Chemistry Laboratory,
Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
- Department
of Chemistry and Photon Science Institute, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
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18
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Williams L, Tischlik S, Scherer A, Fischer JWA, Drescher M. Site-directed attachment of photoexcitable spin labels for light-induced pulsed dipolar spectroscopy. Chem Commun (Camb) 2020; 56:14669-14672. [PMID: 33159780 DOI: 10.1039/d0cc03101a] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Photoexcited triplet states are gaining popularity as spin labels in pulsed electron paramagnetic resonance (EPR) spectroscopy. Here, we demonstrate that the fluorophores Eosin Y, Rose Bengal and Atto Thio12 are suitable markers for distance determination by laser-induced magnetic dipole (LaserIMD) spectroscopy in proteins that lack an intrinsic photoexcitable center.
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Affiliation(s)
- Lara Williams
- Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany.
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19
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Fábregas Ibáñez L, Jeschke G, Stoll S. DeerLab: a comprehensive software package for analyzing dipolar electron paramagnetic resonance spectroscopy data. MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2020; 1:209-224. [PMID: 34568875 PMCID: PMC8462493 DOI: 10.5194/mr-1-209-2020] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 09/21/2020] [Indexed: 05/09/2023]
Abstract
Dipolar EPR spectroscopy (DEER and other techniques) enables the structural characterization of macromolecular and biological systems by measurement of distance distributions between unpaired electrons on a nanometer scale. The inference of these distributions from the measured signals is challenging due to the ill-posed nature of the inverse problem. Existing analysis tools are scattered over several applications with specialized graphical user interfaces. This renders comparison, reproducibility, and method development difficult. To remedy this situation, we present DeerLab, an open-source software package for analyzing dipolar EPR data that is modular and implements a wide range of methods. We show that DeerLab can perform one-step analysis based on separable non-linear least squares, fit dipolar multi-pathway models to multi-pulse DEER data, run global analysis with non-parametric distributions, and use a bootstrapping approach to fully quantify the uncertainty in the analysis.
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Affiliation(s)
- Luis Fábregas Ibáñez
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Gunnar Jeschke
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Stefan Stoll
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
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20
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Sannikova NE, Timofeev IO, Chubarov AS, Lebedeva NS, Semeikin AS, Kirilyuk IA, Tsentalovich YP, Fedin MV, Bagryanskaya EG, Krumkacheva OA. Application of EPR to porphyrin-protein agents for photodynamic therapy. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2020; 211:112008. [PMID: 32932136 DOI: 10.1016/j.jphotobiol.2020.112008] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 07/17/2020] [Accepted: 08/21/2020] [Indexed: 12/19/2022]
Abstract
Recently, a new type of spin labels based on photoexcited triplet molecules was proposed for nanometer scale distance measurements by pulsed dipolar electron paramagnetic resonance (PD EPR). However, such molecules are also actively used within biological complexes as photosensitizers for photodynamic therapy (PDT) of cancer. Up to date, the idea of using the photoexcited triplets simultaneously as PDT agents and as spin labels for PD EPR has never been employed. In this work, we demonstrate that PD EPR in conjunction with other methods provides valuable information on the structure and function of PDT candidate complexes, exemplified here with porphyrins bound to human serum albumin (HSA). Two distinct porphyrins with different properties were used: amphiphilic meso-tetrakis(4-hydroxyphenyl)porphyrin (mTHPP) and water soluble cationic meso-tetrakis(N-methyl-4-pyridyl)porphyrin (TMPyP4); HSA was singly nitroxide-labeled to provide a second tag for PD EPR measurements. We found that TMPyP4 locates in a cavity at the center of the four-helix bundle of HSA subdomain IB, close to the interface with solvent, thus being readily accessible to oxygen. As a result, the photolysis of the complex leads to photooxidation of HSA by generated singlet oxygen and causes structural perturbation of the protein. Contrary, in case of mTHPP porphyrin, the binding occurs at the proton-rich pocket of HSA subdomain IIIA, where the access of oxygen to a photosensitizer is hindered. Structural data of PD EPR were supported by other EPR techniques, laser flash photolysis and protein photocleavage studies. Therefore, pulsed EPR on complexes of proteins with photoexcited triplets is a promising approach for gaining structural and functional insights into such PDT agents.
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Affiliation(s)
| | - Ivan O Timofeev
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia
| | - Alexey S Chubarov
- Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia
| | | | | | - Igor A Kirilyuk
- N.N. Vorozhtsov Institute of Organic Chemistry SB RAS, 630090 Novosibirsk, Russia
| | | | - Matvey V Fedin
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia; Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia.
| | - Elena G Bagryanskaya
- N.N. Vorozhtsov Institute of Organic Chemistry SB RAS, 630090 Novosibirsk, Russia.
| | - Olesya A Krumkacheva
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia; Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russia.
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21
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Sannikova N, Timofeev I, Bagryanskaya E, Bowman M, Fedin M, Krumkacheva O. Electron Spin Relaxation of Photoexcited Porphyrin in Water-Glycerol Glass. Molecules 2020; 25:E2677. [PMID: 32527023 PMCID: PMC7321249 DOI: 10.3390/molecules25112677] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 06/05/2020] [Accepted: 06/06/2020] [Indexed: 02/07/2023] Open
Abstract
Recently, the photoexcited triplet state of porphyrin was proposed as a promising spin-label for pulsed dipolar electron paramagnetic resonance (EPR). Herein, we report the factors that determine the electron spin echo dephasing of the photoexcited porphyrin in a water-glycerol matrix. The electron spin relaxation of a water-soluble porphyrin was measured by Q-band EPR, and the temperature dependence and the effect of solvent deuteration on the relaxation times were studied. The phase memory relaxation rate (1/Tm) is noticeably affected by solvent nuclei and is substantially faster in protonated solvents than in deuterated solvents. The Tm is as large as 13-17 μs in deuterated solvent, potentially expanding the range of distances available for measurement by dipole spectroscopy with photoexcited porphyrin. The 1/Tm depends linearly on the degree of solvent deuteration and can be used to probe the environment of a porphyrin in or near a biopolymer, including the solvent accessibility of porphyrins used in photodynamic therapy. We characterized the noncovalent binding of porphyrin to human serum albumin (HSA) from 1/Tm and electron spin echo envelope modulation (ESEEM) and found that porphyrin is quite exposed to solvent on the surface of HSA. The 1/Tm and ESEEM are equally effective and provide complementary methods to determine the solvent accessibility of a porphyrin bound to protein or to determine the location of the porphyrin.
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Affiliation(s)
- Natalya Sannikova
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia; (N.S.); (I.T.)
| | - Ivan Timofeev
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia; (N.S.); (I.T.)
| | - Elena Bagryanskaya
- N.N. Vorozhtsov Institute of Organic Chemistry SB RAS, 630090 Novosibirsk, Russia
| | - Michael Bowman
- N.N. Vorozhtsov Institute of Organic Chemistry SB RAS, 630090 Novosibirsk, Russia
- Department of Chemistry & Biochemistry, University of Alabama, Tuscaloosa, AL 35487-0336, USA
| | - Matvey Fedin
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia; (N.S.); (I.T.)
| | - Olesya Krumkacheva
- International Tomography Center SB RAS, 630090 Novosibirsk, Russia; (N.S.); (I.T.)
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22
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Zhang Y, Li Z, Feng Y, Guo H, Wen H, Tang J, Liu J. High-sensitivity DC magnetic field detection with ensemble NV centers by pulsed quantum filtering technology. OPTICS EXPRESS 2020; 28:16191-16201. [PMID: 32549446 DOI: 10.1364/oe.392279] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 05/06/2020] [Indexed: 06/11/2023]
Abstract
Continuous wave optically detected magnetic resonance (CW-ODMR) is a practical way to study the sensitivity of the DC magnetic field. However, in large ensemble nitrogen-vacancy (NV) defects, the simultaneous excitation of microwave and laser will deteriorate the parameters of the ODMR spectrum and some unwanted sideband excitations caused by P1 electron spins will also bring challenges to further improve the sensitivity and signal quality. Here, we first achieve the CW-ODMR and acquire DC photon-shot-noise-limited magnetic sensitivity of 12nT/Hz. Different from the conventional method, we take advantage of pulsed quantum filtering (PQF) technology to eliminate such impacts above and demonstrate a sensitivity of about 1nT/Hz, which an order of magnitude enhancement over CW-ODMR. We find this method provides simple but effective support for relevant high-sensitivity DC magnetometry and obtains pure resonance signal when using large ensemble NV- defects.
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23
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Scherer A, Tischlik S, Weickert S, Wittmann V, Drescher M. Optimising broadband pulses for DEER depends on concentration and distance range of interest. MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2020; 1:59-74. [PMID: 37904889 PMCID: PMC10500711 DOI: 10.5194/mr-1-59-2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 04/26/2020] [Indexed: 11/01/2023]
Abstract
EPR distance determination in the nanometre region has become an important tool for studying the structure and interaction of macromolecules. Arbitrary waveform generators (AWGs), which have recently become commercially available for EPR spectrometers, have the potential to increase the sensitivity of the most common technique, double electron-electron resonance (DEER, also called PELDOR), as they allow the generation of broadband pulses. There are several families of broadband pulses, which are different in general pulse shape and the parameters that define them. Here, we compare the most common broadband pulses. When broadband pulses lead to a larger modulation depth, they also increase the background decay of the DEER trace. Depending on the dipolar evolution time, this can significantly increase the noise level towards the end of the form factor and limit the potential increase in the modulation-to-noise ratio (MNR). We found asymmetric hyperbolic secant (HS{ 1 , 6 } ) pulses to perform best for short DEER traces, leading to a MNR improvement of up to 86 % compared to rectangular pulses. For longer traces we found symmetric hyperbolic secant (HS{ 1 , 1 } ) pulses to perform best; however, the increase compared to rectangular pulses goes down to 43 %.
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Affiliation(s)
- Andreas Scherer
- Department of Chemistry and Konstanz Research School Chemical Biology,
University of Konstanz, Konstanz, Germany
| | - Sonja Tischlik
- Department of Chemistry and Konstanz Research School Chemical Biology,
University of Konstanz, Konstanz, Germany
| | - Sabrina Weickert
- Department of Chemistry and Konstanz Research School Chemical Biology,
University of Konstanz, Konstanz, Germany
| | - Valentin Wittmann
- Department of Chemistry and Konstanz Research School Chemical Biology,
University of Konstanz, Konstanz, Germany
| | - Malte Drescher
- Department of Chemistry and Konstanz Research School Chemical Biology,
University of Konstanz, Konstanz, Germany
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24
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Dal Farra MG, Martin C, Bergantino E, Kandrashkin YE, van der Est A, Di Valentin M. Electron spin polarization transfer induced by triplet–radical interactions in the weakly coupled regime. Phys Chem Chem Phys 2020; 22:19982-19991. [DOI: 10.1039/d0cp03565c] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
We report the observation of electron spin polarization transfer from the triplet state of a porphyrin to a weakly coupled nitroxide radical in a mutant of human neuroglobin (NGB).
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Affiliation(s)
| | - Caterina Martin
- Dipartimento di Biologia
- Università degli Studi di Padova
- I-35131 Padova
- Italy
| | | | - Yuri E. Kandrashkin
- Zavoisky Physical-Technical Institute
- FRC Kazan Scientific Center of RAS
- Kazan 420029
- Russian Federation
| | | | - Marilena Di Valentin
- Dipartimento di Scienze Chimiche
- Università degli studi di Padova
- 35131 Padova
- Italy
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25
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Kuzhelev AA, Tormyshev VM, Plyusnin VF, Rogozhnikova OY, Edeleva MV, Veber SL, Bagryanskaya EG. Photochemistry of tris(2,3,5,6-tetrathiaaryl)methyl radicals in various solutions. Phys Chem Chem Phys 2020; 22:1019-1026. [DOI: 10.1039/c9cp06213k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A detailed mechanism of TAM photolysis was studied and includes photoionization of the TAM radical with the formation of carbocation and further conversion of the carbocation under aerobic conditions into quinone-methide and under anaerobic conditions supposedly into an aromatic carbene.
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Affiliation(s)
- Andrey A. Kuzhelev
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS
- Novosibirsk 630090
- Russia
| | - Victor M. Tormyshev
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS
- Novosibirsk 630090
- Russia
- Novosibirsk State University
- Novosibirsk 630090
| | - Victor F. Plyusnin
- Novosibirsk State University
- Novosibirsk 630090
- Russia
- Voevodsky Institute of Chemical Kinetics and Combustion
- SB RAS
| | - Olga Yu. Rogozhnikova
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS
- Novosibirsk 630090
- Russia
| | - Mariya V. Edeleva
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS
- Novosibirsk 630090
- Russia
- Novosibirsk State University
- Novosibirsk 630090
| | - Sergey L. Veber
- Novosibirsk State University
- Novosibirsk 630090
- Russia
- International Tomography Center SB RAS
- Novosibirsk 630090
| | - Elena G. Bagryanskaya
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS
- Novosibirsk 630090
- Russia
- Novosibirsk State University
- Novosibirsk 630090
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26
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Goldfarb D. Pulse EPR in biological systems - Beyond the expert's courtyard. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 306:102-108. [PMID: 31337564 DOI: 10.1016/j.jmr.2019.07.038] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 06/07/2019] [Accepted: 07/08/2019] [Indexed: 05/14/2023]
Abstract
Application of EPR to biological systems includes many techniques and applications. In this short perspective, which dares to look into the future, I focus on pulse EPR, which is my field of expertise. Generally, pulse EPR techniques can be divided into two main groups: (1) hyperfine spectroscopy, which explores electron-nuclear interactions, and (2) pulse-dipolar (PD) EPR spectroscopy, which is based on electron-electron spin interactions. Here I focus on PD-EPR because it has a better chance of becoming a widely applied, easy-to-use table-top method to study the structural and dynamic aspects of bio-molecules. I will briefly introduce this technique, its current state of the art, the challenges it is facing, and finally I will describe futuristic scenarios of low-cost PD-EPR approaches that can cross the diffusion barrier from the core of experts to the bulk of the scientific community.
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Affiliation(s)
- Daniella Goldfarb
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel.
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27
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Krumkacheva OA, Timofeev IO, Politanskaya LV, Polienko YF, Tretyakov EV, Rogozhnikova OY, Trukhin DV, Tormyshev VM, Chubarov AS, Bagryanskaya EG, Fedin MV. Triplet Fullerenes as Prospective Spin Labels for Nanoscale Distance Measurements by Pulsed Dipolar EPR Spectroscopy. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201904152] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Olesya A. Krumkacheva
- International Tomography Center SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Ivan O. Timofeev
- International Tomography Center SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Larisa V. Politanskaya
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Yuliya F. Polienko
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Evgeny V. Tretyakov
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Olga Yu. Rogozhnikova
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Dmitry V. Trukhin
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Victor M. Tormyshev
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Alexey S. Chubarov
- Institute of Chemical Biology and Fundamental Medicine SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Elena G. Bagryanskaya
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
| | - Matvey V. Fedin
- International Tomography Center SB RAS Novosibirsk 630090 Russia
- Novosibirsk State University Novosibirsk 630090 Russia
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28
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Krumkacheva OA, Timofeev IO, Politanskaya LV, Polienko YF, Tretyakov EV, Rogozhnikova OY, Trukhin DV, Tormyshev VM, Chubarov AS, Bagryanskaya EG, Fedin MV. Triplet Fullerenes as Prospective Spin Labels for Nanoscale Distance Measurements by Pulsed Dipolar EPR Spectroscopy. Angew Chem Int Ed Engl 2019; 58:13271-13275. [PMID: 31322814 DOI: 10.1002/anie.201904152] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 07/11/2019] [Indexed: 11/11/2022]
Abstract
Precise nanoscale distance measurements by pulsed electron paramagnetic resonance (EPR) spectroscopy play a crucial role in structural studies of biomolecules. The properties of the spin labels used in this approach determine the sensitivity limits, attainable distances, and proximity to biological conditions. Herein, we propose and validate the use of photoexcited fullerenes as spin labels for pulsed dipolar (PD) EPR distance measurements. Hyperpolarization and the narrower spectrum of fullerenes compared to other triplets (e.g., porphyrins) boost the sensitivity, and superior relaxation properties allow PD EPR measurements up to a near-room temperature. This approach is demonstrated using fullerene-nitroxide and fullerene-triarylmethyl pairs, as well as a supramolecular complex of fullerene with nitroxide-labeled protein. Photoexcited triplet fullerenes can be considered as new spin labels with outstanding spectroscopic properties for future structural studies of biomolecules.
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Affiliation(s)
- Olesya A Krumkacheva
- International Tomography Center SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Ivan O Timofeev
- International Tomography Center SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Larisa V Politanskaya
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Yuliya F Polienko
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Evgeny V Tretyakov
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Olga Yu Rogozhnikova
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Dmitry V Trukhin
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Victor M Tormyshev
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Alexey S Chubarov
- Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Elena G Bagryanskaya
- N.N.Vorozhtsov Institute of Organic Chemistry SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Matvey V Fedin
- International Tomography Center SB RAS, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
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29
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Serrer K, Matt C, Sokolov M, Kacprzak S, Schleicher E, Weber S. Application of commercially available fluorophores as triplet spin probes in EPR spectroscopy. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1608379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Kerstin Serrer
- Institute of Physical Chemistry, University of Freiburg, Freiburg, Germany
| | - Clemens Matt
- Institute of Physical Chemistry, University of Freiburg, Freiburg, Germany
| | - Monja Sokolov
- Institute of Physical Chemistry, University of Freiburg, Freiburg, Germany
| | - Sylwia Kacprzak
- Institute of Physical Chemistry, University of Freiburg, Freiburg, Germany
| | - Erik Schleicher
- Institute of Physical Chemistry, University of Freiburg, Freiburg, Germany
| | - Stefan Weber
- Institute of Physical Chemistry, University of Freiburg, Freiburg, Germany
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30
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Dal Farra MG, Richert S, Martin C, Larminie C, Gobbo M, Bergantino E, Timmel CR, Bowen AM, Di Valentin M. Light-Induced Pulsed EPR Dipolar Spectroscopy on a Paradigmatic Hemeprotein. Chemphyschem 2019; 20:931-935. [PMID: 30817078 PMCID: PMC6618045 DOI: 10.1002/cphc.201900139] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 02/27/2019] [Indexed: 01/12/2023]
Abstract
Light-induced pulsed EPR dipolar spectroscopic methods allow the determination of nanometer distances between paramagnetic sites. Here we employ orthogonal spin labels, a chromophore triplet state and a stable radical, to carry out distance measurements in singly nitroxide-labeled human neuroglobin. We demonstrate that Zn-substitution of neuroglobin, to populate the Zn(II) protoporphyrin IX triplet state, makes it possible to perform light-induced pulsed dipolar experiments on hemeproteins, extending the use of light-induced dipolar spectroscopy to this large class of metalloproteins. The versatility of the method is ensured by the employment of different techniques: relaxation-induced dipolar modulation enhancement (RIDME) is applied for the first time to the photoexcited triplet state. In addition, an alternative pulse scheme for laser-induced magnetic dipole (LaserIMD) spectroscopy, based on the refocused-echo detection sequence, is proposed for accurate zero-time determination and reliable distance analysis.
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Affiliation(s)
| | - Sabine Richert
- Centre for Advanced Electron Spin Resonance (CAESR) Department of Chemistry, Inorganic Chemistry LaboratoryUniversity of OxfordSouth Parks RoadOxfordOX1 3QRUK
- current affiliation: Institute of Physical ChemistryUniversity of FreiburgAlbertstr. 2179104FreiburgGermany
| | - Caterina Martin
- Department of BiologyUniversity of Padovaviale G. Colombo 335121PadovaItaly
- current affiliation: Groningen Biomolecular Science and Biotechnology InstituteUniversity of Groningen9700 ABGroningenThe Netherlands
| | - Charles Larminie
- Centre for Advanced Electron Spin Resonance (CAESR) Department of Chemistry, Inorganic Chemistry LaboratoryUniversity of OxfordSouth Parks RoadOxfordOX1 3QRUK
| | - Marina Gobbo
- Department of Chemical SciencesUniversity of PadovaVia Marzolo 135131PadovaItaly
| | | | - Christiane R. Timmel
- Centre for Advanced Electron Spin Resonance (CAESR) Department of Chemistry, Inorganic Chemistry LaboratoryUniversity of OxfordSouth Parks RoadOxfordOX1 3QRUK
| | - Alice M. Bowen
- Centre for Advanced Electron Spin Resonance (CAESR) Department of Chemistry, Inorganic Chemistry LaboratoryUniversity of OxfordSouth Parks RoadOxfordOX1 3QRUK
| | - Marilena Di Valentin
- Department of Chemical SciencesUniversity of PadovaVia Marzolo 135131PadovaItaly
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31
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Milikisiyants S, Voinov MA, Marek A, Jafarabadi M, Liu J, Han R, Wang S, Smirnov AI. Enhancing sensitivity of Double Electron-Electron Resonance (DEER) by using Relaxation-Optimized Acquisition Length Distribution (RELOAD) scheme. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 298:115-126. [PMID: 30544015 PMCID: PMC6894391 DOI: 10.1016/j.jmr.2018.12.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 12/02/2018] [Accepted: 12/04/2018] [Indexed: 05/05/2023]
Abstract
Over the past decades pulsed electron-electron double resonance (PELDOR), often called double electron-electron resonance (DEER), became one of the major spectroscopic tools for measurements of nanometer-scale distances and distance distributions in non-crystalline biological and chemical systems. The method is based on detecting the amplitude of the primary (3-pulse DEER) or refocused (4-pulse DEER) spin echo for the so-called "observer" spins when the other spins coupled to the former by a dipolar interaction are flipped by a "pump" pulse at another EPR frequency. While the timing of the pump pulse is varied in steps, the positions of the observer pulses are typically fixed. For such a detection scheme the total length of the observer pulse train and the electron spin memory time determine the amplitude of the detected echo signal. Usually, the distance range considerations in DEER experiments dictate the total length of the observer pulse train to exceed the phase memory time by a factor of few and this leads to a dramatic loss of the signal-to-noise ratio (SNR). While the acquisition of the DEER signal seems to be irrational under such conditions, it is currently the preferred way to conduct DEER because of an effective filtering out of all other unwanted interactions. Here we propose a novel albeit simple approach to improve DEER sensitivity and decrease data acquisition time by introducing the signal acquisition scheme based on RELaxation Optimized Acquisition (Length) Distribution (DEER-RELOAD). In DEER-RELOAD the dipolar phase evolution signal is acquired in multiple segments in which the observer pulses are fixed at the positions to optimize SNR just for that specific segment. The length of the segment is chosen to maximize the signal acquisition efficiency according the phase relaxation properties of the spin system. The total DEER trace is then obtained by "stitching" the multiple segments into a one continuous trace. The utility of the DEER-RELOAD acquisition scheme has been demonstrated on an example of the standard 4-pulse DEER sequence applied to two membrane protein complexes labeled with nitroxides. While theoretical gains from the DEER-RELOAD scheme increase with the number of stitched segments, in practice, even dividing the acquisition of the DEER trace into two segments may improve SNR by a factor of >3, as it has been demonstrated for one of these two membrane proteins.
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Affiliation(s)
- Sergey Milikisiyants
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA
| | - Maxim A Voinov
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA
| | - Antonin Marek
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA
| | - Morteza Jafarabadi
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA
| | - Jing Liu
- Beijing Nuclear Magnetic Resonance Center and College of Chemistry and Molecular Engineering, Peking University, 5 Yiheyuan Road, Haidian, Beijing 100871, People's Republic of China
| | - Rong Han
- Beijing Nuclear Magnetic Resonance Center and College of Chemistry and Molecular Engineering, Peking University, 5 Yiheyuan Road, Haidian, Beijing 100871, People's Republic of China
| | - Shenlin Wang
- Beijing Nuclear Magnetic Resonance Center and College of Chemistry and Molecular Engineering, Peking University, 5 Yiheyuan Road, Haidian, Beijing 100871, People's Republic of China
| | - Alex I Smirnov
- Beijing Nuclear Magnetic Resonance Center and College of Chemistry and Molecular Engineering, Peking University, 5 Yiheyuan Road, Haidian, Beijing 100871, People's Republic of China.
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32
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Bieber A, Bücker D, Drescher M. Light-induced dipolar spectroscopy - A quantitative comparison between LiDEER and LaserIMD. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 296:29-35. [PMID: 30199790 DOI: 10.1016/j.jmr.2018.08.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 08/07/2018] [Accepted: 08/22/2018] [Indexed: 05/14/2023]
Abstract
Nanometric distance measurements with EPR spectroscopy yield crucial information on the structure and interactions of macromolecules in complex systems. The range of suitable spin labels for such measurements was recently expanded with a new class of light-inducible labels: the triplet state of porphyrins. Importantly, accurate distance measurements between a triplet label and a nitroxide have been reported with two distinct light-induced spectroscopy techniques, (light-induced) triplet-nitroxide DEER (LiDEER) and laser-induced magnetic dipole spectroscopy (LaserIMD). In this work, we set out to quantitatively compare the two techniques under equivalent conditions at Q band. Since we find that LiDEER using a rectangular pump pulse does not reach the high modulation depth that can be achieved with LaserIMD, we further explore the possibility of improving the LiDEER experiment with chirp inversion pulses. LiDEER employing a broadband pump pulse results in a drastic improvement of the modulation depth. The relative performance of chirp LiDEER and Laser-IMD in terms of modulation-to-noise ratio is found to depend on the dipolar evolution time: While LaserIMD yields higher modulation-to-noise ratios than LiDEER at short dipolar evolution times (τ=2μs), the high phase memory time of the triplet spins causes the situation to revert at τ=6μs.
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Affiliation(s)
- Anna Bieber
- Department of Chemistry and Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstraße 10, 78464 Konstanz, Germany
| | - Dennis Bücker
- Department of Chemistry and Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstraße 10, 78464 Konstanz, Germany
| | - Malte Drescher
- Department of Chemistry and Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstraße 10, 78464 Konstanz, Germany.
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33
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Dal Farra MG, Ciuti S, Gobbo M, Carbonera D, Di Valentin M. Triplet-state spin labels for highly sensitive pulsed dipolar spectroscopy. Mol Phys 2018. [DOI: 10.1080/00268976.2018.1503749] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- M. G. Dal Farra
- Dipartimento di Scienze Chimiche, Università degli studi di Padova, Padova, Italy
| | - S. Ciuti
- Dipartimento di Scienze Chimiche, Università degli studi di Padova, Padova, Italy
| | - M. Gobbo
- Dipartimento di Scienze Chimiche, Università degli studi di Padova, Padova, Italy
| | - D. Carbonera
- Dipartimento di Scienze Chimiche, Università degli studi di Padova, Padova, Italy
| | - M. Di Valentin
- Dipartimento di Scienze Chimiche, Università degli studi di Padova, Padova, Italy
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34
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Hintze C, Morgen TO, Drescher M. Heavy-atom effect on optically excited triplet state kinetics. PLoS One 2017; 12:e0184239. [PMID: 29155822 PMCID: PMC5695852 DOI: 10.1371/journal.pone.0184239] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 08/21/2017] [Indexed: 12/25/2022] Open
Abstract
In several fields of research, like e.g. photosensitization, photovoltaics, organic electroluminescent devices, dynamic nuclear polarization, or pulsed dipolar electron paramagnetic resonance spectroscopy, triplet state kinetics play an important role. It is therefore desirable to tailor the kinetics of photoexcited triplet states, e.g. by exploiting the intramolecular heavy-atom effect, and to determine the respective kinetic parameters. In this work, we set out to systematically investigate the photoexcited triplet state kinetics of a series of haloanthracenes by time-resolved electron paramagnetic resonance spectroscopy in combination with synchronized laser excitation. For this purpose, a procedure to simulate time traces by solving the differential equation system governing the triplet kinetics numerically is developed. This way, spin lattice relaxation rates and zero-field triplet life times are obtained concurrently by a global fit to experimental data measured at three different cryogenic temperatures.
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Affiliation(s)
| | | | - Malte Drescher
- Fachbereich Chemie, Universität Konstanz, Konstanz, Germany
- * E-mail:
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35
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Gmeiner C, Klose D, Mileo E, Belle V, Marque SRA, Dorn G, Allain FHT, Guigliarelli B, Jeschke G, Yulikov M. Orthogonal Tyrosine and Cysteine Site-Directed Spin Labeling for Dipolar Pulse EPR Spectroscopy on Proteins. J Phys Chem Lett 2017; 8:4852-4857. [PMID: 28933855 DOI: 10.1021/acs.jpclett.7b02220] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Site-directed spin labeling of native tyrosine residues in isolated domains of the protein PTBP1, using a Mannich-type reaction, was combined with conventional spin labeling of cysteine residues. Double electron-electron resonance (DEER) EPR measurements were performed for both the nitroxide-nitroxide and Gd(III)-nitroxide label combinations within the same protein molecule. For the prediction of distance distributions from a structure model, rotamer libraries were generated for the two linker forms of the tyrosine-reactive isoindoline-based nitroxide radical Nox. Only moderate differences exist between the spatial spin distributions for the two linker forms of Nox. This strongly simplifies DEER data analysis, in particular, if only mean distances need to be predicted.
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Affiliation(s)
- Christoph Gmeiner
- Laboratory of Physical Chemistry, ETH Zurich , Zurich 8093, Switzerland
| | - Daniel Klose
- Laboratory of Physical Chemistry, ETH Zurich , Zurich 8093, Switzerland
| | - Elisabetta Mileo
- Aix Marseille Univ , CNRS, BIP, Laboratoire de Bioénergétique et Ingénierie des Protéines, Marseille 13402, France
| | - Valérie Belle
- Aix Marseille Univ , CNRS, BIP, Laboratoire de Bioénergétique et Ingénierie des Protéines, Marseille 13402, France
| | - Sylvain R A Marque
- Aix Marseille Univ , CNRS, ICR, Institut de Chimie Radicalaire, Marseille 13397, France
- N. N. Vorozhtsov Novosibirsk Insititute of Organic Chemistry , 630090 Novosibirsk, Russia
| | - Georg Dorn
- Institute of Molecular Biology and Biophysics, ETH Zurich , Zurich 8093, Switzerland
| | - Frédéric H T Allain
- Institute of Molecular Biology and Biophysics, ETH Zurich , Zurich 8093, Switzerland
| | - Bruno Guigliarelli
- Aix Marseille Univ , CNRS, BIP, Laboratoire de Bioénergétique et Ingénierie des Protéines, Marseille 13402, France
| | - Gunnar Jeschke
- Laboratory of Physical Chemistry, ETH Zurich , Zurich 8093, Switzerland
| | - Maxim Yulikov
- Laboratory of Physical Chemistry, ETH Zurich , Zurich 8093, Switzerland
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36
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Richert S, Tait CE, Timmel CR. Delocalisation of photoexcited triplet states probed by transient EPR and hyperfine spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 280:103-116. [PMID: 28579096 DOI: 10.1016/j.jmr.2017.01.005] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Revised: 01/05/2017] [Accepted: 01/07/2017] [Indexed: 05/22/2023]
Abstract
Photoexcited triplet states play a crucial role in photochemical mechanisms: long known to be of paramount importance in the study of photosynthetic reaction centres, they have more recently also been shown to play a major role in a number of applications in the field of molecular electronics. Their characterisation is crucial for an improved understanding of these processes with a particular focus on the determination of the spatial distribution of the triplet state wavefunction providing information on charge and energy transfer efficiencies. Currently, active research in this field is mostly focussed on the investigation of materials for organic photovoltaics (OPVs) and organic light emitting diodes (OLEDs). As the properties of triplet states and their spatial extent are known to have a major impact on device performance, a detailed understanding of the factors governing triplet state delocalisation is at the basis of the further development and improvement of these devices. Electron Paramagnetic Resonance (EPR) has proven a valuable tool in the study of triplet state properties and both experimental methods as well as data analysis and interpretation techniques have continuously improved over the last few decades. In this review, we discuss the theoretical and practical aspects of the investigation of triplet states and triplet state delocalisation by transient continuous wave and pulse EPR and highlight the advantages and limitations of the presently available techniques and the current trends in the field. Application of EPR in the study of triplet state delocalisation is illustrated on the example of linear multi-porphyrin chains designed as molecular wires.
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Affiliation(s)
- Sabine Richert
- Centre for Advanced Electron Spin Resonance (CAESR), Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom.
| | - Claudia E Tait
- Department of Chemistry, University of Washington, Seattle, WA 98195, United States.
| | - Christiane R Timmel
- Centre for Advanced Electron Spin Resonance (CAESR), Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom.
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37
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Hintze C, Steiner UE, Drescher M. Photoexcited Triplet State Kinetics Studied by Electron Paramagnetic Resonance Spectroscopy. Chemphyschem 2016; 18:6-16. [DOI: 10.1002/cphc.201600868] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 10/07/2016] [Indexed: 11/08/2022]
Affiliation(s)
| | | | - Malte Drescher
- Fachbereich Chemie Universität Konstanz 78457 Konstanz Germany
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38
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Ivanov MY, Prikhod’ko SA, Adonin NY, Bagryanskaya EG, Fedin MV. Influence of C2-Methylation of Imidazolium Based Ionic Liquids on Photoinduced Spin Dynamics of the Dissolved ZnTPP Studied by Time-Resolved EPR. Z PHYS CHEM 2016. [DOI: 10.1515/zpch-2016-0820] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Abstract
Unusual physical properties of ionic liquids (ILs) can be implemented in many different applications and are very sensitive to the structure of IL. In this work we investigate the spin dynamics of probe molecule Zn tetraphenylporphyrin (ZnTPP) dissolved in a series of ILs using time-resolved electron paramagnetic resonance (TR EPR). We compare the TR EPR characteristics in C2-methylated imidazolium-based ILs [bmmim]BF4 and [bmmim]PF6 and in their C2-protonated analogs [bmim]BF4 and [bmim]PF6 to assess the influence of C2-methylation. The corresponding TR EPR signatures are drastically different in the two types of ILs. The analysis of experimental data allows assumptions that the ZnTPP molecule is distorted in C2-methylated ILs, contrary to other organic media and C2-protonated analogs. The mobility of ZnTPP in C2-methylated ILs is smaller compared to that in C2-protonated analogs, implying different microenvironment formed around dissolved ZnTPP.
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Affiliation(s)
- Mikhail Yu. Ivanov
- International Tomography Center SB RAS, 630090, Novosibirsk, Russian Federation
- Novosibirsk State University, 630090, Novosibirsk, Russian Federation
| | | | - Nicolay Yu. Adonin
- Boreskov Institute of Catalysis SB RAS, 630090, Novosibirsk, Russian Federation
| | - Elena G. Bagryanskaya
- Novosibirsk State University, 630090, Novosibirsk, Russian Federation
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry SB RAS, 630090, Novosibirsk, Russian Federation
| | - Matvey V. Fedin
- Novosibirsk State University, 630090, Novosibirsk, Russian Federation
- International Tomography Center SB RAS, Institutskaya str. 3a, 630090, Novosibirsk, Russian Federation , Tel.: +7 383 3301276
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