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Endeward B, Bretschneider M, Trenkler P, Prisner TF. Implementation and applications of shaped pulses in EPR. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2023; 136-137:61-82. [PMID: 37716755 DOI: 10.1016/j.pnmrs.2023.04.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Revised: 04/12/2023] [Accepted: 04/26/2023] [Indexed: 09/18/2023]
Abstract
In this review, we describe the application of shaped pulses for EPR spectroscopy. Pulses generated by fast arbitrary waveform generators are mostly used in the field of EPR spectroscopy for broadband (200 MHz-1 GHz) excitation of paramagnetic species. The implementation and optimization of such broadband pulses in existing EPR spectrometers, often designed and optimized for short rectangular microwave pulses, is demanding. Therefore, a major part of this review will describe in detail the implementation, testing and optimization of shaped pulses in existing EPR spectrometers. Additionally, we review applications using such pulses for broadband inversion of longitudinal magnetization as well as for the creation and manipulation of transverse magnetization in the field of dipolar and hyperfine EPR spectroscopy. They demonstrate the great potential of shaped pulses to improve the performance of pulsed EPR experiments. We give a brief theoretical description of shaped pulses and their limitations, especially for adiabatic pulses, most often used in EPR. We believe that this review can on the one hand be of practical use to EPR groups starting to work with such pulses, and on the other hand give readers an overview of the state of the art of shaped pulse applications in EPR spectroscopy.
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Affiliation(s)
- Burkhard Endeward
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 7, 60438 Frankfurt am Main, Germany
| | - Matthias Bretschneider
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 7, 60438 Frankfurt am Main, Germany
| | - Paul Trenkler
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 7, 60438 Frankfurt am Main, Germany
| | - Thomas F Prisner
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 7, 60438 Frankfurt am Main, Germany.
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2
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Mardini M, Palani RS, Ahmad IM, Mandal S, Jawla SK, Bryerton E, Temkin RJ, Sigurdsson ST, Griffin RG. Frequency-swept dynamic nuclear polarization. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 353:107511. [PMID: 37385067 DOI: 10.1016/j.jmr.2023.107511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 06/14/2023] [Accepted: 06/15/2023] [Indexed: 07/01/2023]
Abstract
Dynamic nuclear polarization (DNP) improves the sensitivity of NMR spectroscopy by the transfer of electron polarization to nuclei via irradiation of electron-nuclear transitions with microwaves at the appropriate frequency. For fields > 5 T and using g ∼ 2 electrons as polarizing agents, this requires the availability of microwave sources operating at >140 GHz. Therefore, microwave sources for DNP have generally been continuous-wave (CW) gyrotrons, and more recently solid state, oscillators operating at a fixed frequency and power. This constraint has limited the DNP mechanisms which can be exploited, and stymied the development of new time domain mechanisms. We report here the incorporation of a microwave source enabling facile modulation of frequency, amplitude, and phase at 9 T (250 GHz microwave frequency), and we have used the source for magic-angle spinning (MAS) NMR experiments. The experiments include investigations of CW DNP mechanisms, the advantage of frequency-chirped irradiation, and a demonstration of an Overhauser enhancement of ∼25 with a recently reported water-soluble BDPA radical, highlighting the potential for affordable and compact microwave sources to achieve significant enhancement in aqueous samples, including biological macromolecules. With the development of suitable microwave amplifiers, it should permit exploration of multiple new avenues involving time domain experiments.
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Affiliation(s)
- Michael Mardini
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - Ravi Shankar Palani
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - Iram M Ahmad
- Department of Chemistry, Science Institute, University of Iceland, Reykjavik, Iceland
| | - Sucharita Mandal
- Department of Chemistry, Science Institute, University of Iceland, Reykjavik, Iceland
| | - Sudheer K Jawla
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - Eric Bryerton
- Virginia Diodes Corporation, Charlottesville, VA 22902, United States
| | - Richard J Temkin
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - Snorri Th Sigurdsson
- Department of Chemistry, Science Institute, University of Iceland, Reykjavik, Iceland
| | - Robert G Griffin
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
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Wang X, Peng C, He K, Ji K, Tan X, Han G, Liu Y, Liu Y, Song Y. Intracellular delivery of liposome-encapsulated Finland trityl radicals for EPR oximetry. Analyst 2020; 145:4964-4971. [PMID: 32510063 DOI: 10.1039/d0an00108b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Tetrathiatriarylmethyl (TAM, trityl) radicals have found wide applications in electron paramagnetic resonance (EPR) oximetry. However, the biomedical applications of TAM radicals were exclusively limited to an extracellular region owing to their negatively charged nature. The intracellular delivery of TAM radicals still remains a challenge. In the present work, we report a liposome-based method to encapsulate the water-soluble Finland trityl radical CT-03 for its intracellular delivery. Using the thin lipid film hydration method, CT-03-loaded liposomes were prepared from DSPC/cholesterol/DOTAP with a mean size of 167.5 ± 2.4 nm and a zeta potential of 27.8 ± 0.8 mV. EPR results showed that CT-03 was entrapped into the liposomes and still exhibited good oxygen (O2) sensitivity. Moreover, CT-03 was successfully delivered into HepG2 cells and HUVECs using the CT-03-loaded liposomes. Importantly, the combination of the liposome-encapsulated radical CT-03 and the other TAM radical CT02-H enabled simultaneous measurements of the intracellular and extracellular O2 concentrations and O2 consumption rates in HepG2 cells. Our present study provides a new approach for intracellular delivery of TAM radicals and could significantly expand their biomedical applications.
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Affiliation(s)
- Xing Wang
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin 300070, P. R. China.
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5
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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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6
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Yang Y, Pan BB, Tan X, Yang F, Liu Y, Su XC, Goldfarb D. In-Cell Trityl-Trityl Distance Measurements on Proteins. J Phys Chem Lett 2020; 11:1141-1147. [PMID: 31951412 PMCID: PMC7307952 DOI: 10.1021/acs.jpclett.9b03208] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Double-electron electron resonance (DEER) can be used to track the structural dynamics of proteins in their native environment, the cell. This method provides the distance distribution between two spin labels attached at specific, well-defined positions in a protein. For the method to be viable under in-cell conditions, the spin label and its attachment to the protein should exhibit high chemical stability in the cell. Here we present low-temperature, trityl-trityl DEER distance measurements on two model proteins, PpiB (prolyl cis-trans isomerase from E. coli) and GB1 (immunoglobulin G-binding protein), doubly labeled with the trityl spin label, CT02MA. Both proteins gave in-cell distance distributions similar to those observed in vitro, with maxima at 4.5-5 nm, and the data were further compared with in-cell Gd(III)-Gd(III) DEER obtained for PpiB labeled with BrPSPy-DO3A-Gd(III) at the same positions. These results highlight the challenges of designing trityl tags suitable for in-cell distance determination at ambient temperatures on live cells.
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Affiliation(s)
- Yin Yang
- Department
of Chemical and Biological Physics, Weizmann
Institute of Science, Rehovot 76100, Israel
| | - Bin-Bin Pan
- State
Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation
Center of Chemical Science and Engineering, Nankai University, Tianjin 300071, China
| | - Xiaoli Tan
- Tianjin
Key Laboratory on Technologies Enabling Development of Clinical Therapeutics
and Diagnostics, School of Pharmacy, Tianjin
Medical University, Tianjin 300070, China
| | - Feng Yang
- State
Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation
Center of Chemical Science and Engineering, Nankai University, Tianjin 300071, China
| | - Yangping Liu
- Tianjin
Key Laboratory on Technologies Enabling Development of Clinical Therapeutics
and Diagnostics, School of Pharmacy, Tianjin
Medical University, Tianjin 300070, China
| | - Xun-Cheng Su
- State
Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation
Center of Chemical Science and Engineering, Nankai University, Tianjin 300071, China
| | - Daniella Goldfarb
- Department
of Chemical and Biological Physics, Weizmann
Institute of Science, Rehovot 76100, Israel
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7
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Tan X, Ji K, Wang X, Yao R, Han G, Villamena FA, Zweier JL, Song Y, Rockenbauer A, Liu Y. Discriminative Detection of Biothiols by Electron Paramagnetic Resonance Spectroscopy using a Methanethiosulfonate Trityl Probe. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201912832] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Xiaoli Tan
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and DiagnosticsSchool of PharmacyTianjin Medical University Tianjin 300070 P. R. China
| | - Kaiyun Ji
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and DiagnosticsSchool of PharmacyTianjin Medical University Tianjin 300070 P. R. China
| | - Xing Wang
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and DiagnosticsSchool of PharmacyTianjin Medical University Tianjin 300070 P. R. China
| | - Ru Yao
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and DiagnosticsSchool of PharmacyTianjin Medical University Tianjin 300070 P. R. China
| | - Guifang Han
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and DiagnosticsSchool of PharmacyTianjin Medical University Tianjin 300070 P. R. China
| | - Frederick A. Villamena
- Department of Biological Chemistry and PharmacologyCollege of MedicineThe Ohio State University Columbus OH 43210 USA
| | - Jay L. Zweier
- Center for Biomedical EPR Spectroscopy and ImagingThe Davis Heart and Lung Research Institutethe Division of Cardiovascular MedicineDepartment of Internal MedicineThe Ohio State University Columbus OH 43210 USA
| | - Yuguang Song
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and DiagnosticsSchool of PharmacyTianjin Medical University Tianjin 300070 P. R. China
| | - Antal Rockenbauer
- Institute of Materials and Environmental ChemistryResearch Centre for Natural SciencesHungarian Academy of Sciences 1117 Budapest Hungary
- Department of PhysicsBudapest University of Technology and Economics Budafoki ut 8 1111 Budapest Hungary
| | - Yangping Liu
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and DiagnosticsSchool of PharmacyTianjin Medical University Tianjin 300070 P. R. China
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8
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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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9
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Tan X, Ji K, Wang X, Yao R, Han G, Villamena FA, Zweier JL, Song Y, Rockenbauer A, Liu Y. Discriminative Detection of Biothiols by Electron Paramagnetic Resonance Spectroscopy using a Methanethiosulfonate Trityl Probe. Angew Chem Int Ed Engl 2019; 59:928-934. [PMID: 31657108 DOI: 10.1002/anie.201912832] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Indexed: 12/30/2022]
Abstract
Biothiols, such as glutathione (GSH), homocysteine (Hcy), and cysteine (Cys), coexist in biological systems with diverse biological roles. Thus, analytical techniques that can detect, quantify, and distinguish between multiple biothiols are desirable but challenging. Herein, we demonstrate the simultaneous detection and quantitation of multiple biothiols, including up to three different biothiols in a single sample, using electron paramagnetic resonance (EPR) spectroscopy and a trityl-radical-based probe (MTST). We term this technique EPR thiol-trapping. MTST could trap thiols through its methanethiosulfonate group to form the corresponding disulfide conjugate with an EPR spectrum characteristic of the trapped thiol. MTST was used to investigate effects of l-buthionine sulfoximine (BSO) and pyrrolidine dithiocarbamate (PDTC) on the efflux of GSH and Cys from HepG2 cells.
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Affiliation(s)
- Xiaoli Tan
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin, 300070, P. R. China
| | - Kaiyun Ji
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin, 300070, P. R. China
| | - Xing Wang
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin, 300070, P. R. China
| | - Ru Yao
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin, 300070, P. R. China
| | - Guifang Han
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin, 300070, P. R. China
| | - Frederick A Villamena
- Department of Biological Chemistry and Pharmacology, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - Jay L Zweier
- Center for Biomedical EPR Spectroscopy and Imaging, The Davis Heart and Lung Research Institute, the Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - Yuguang Song
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin, 300070, P. R. China
| | - Antal Rockenbauer
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, 1117, Budapest, Hungary.,Department of Physics, Budapest University of Technology and Economics, Budafoki ut 8, 1111, Budapest, Hungary
| | - Yangping Liu
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin, 300070, P. R. China
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10
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Prisner TF. Shaping EPR: Phase and amplitude modulated microwave pulses. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 306:98-101. [PMID: 31324586 DOI: 10.1016/j.jmr.2019.07.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 05/11/2019] [Accepted: 07/08/2019] [Indexed: 06/10/2023]
Abstract
The advent of fast arbitrary waveform generators in the sub-nanosecond time regime recently enabled new experimental developments in the field of pulsed EPR. In this article, the new possibilities of such fast phase/amplitude modulated microwave pulses are shortly described with respect to applications in pulsed dipolar spectroscopy. Some of the specific challenges of an accurate creation of such pulses in the field of EPR are outlined. Finally, a short outlook of potential applications is given and some specific experimental conditions are discussed, where shaped pulses might have an especially important impact in the future.
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Affiliation(s)
- Thomas F Prisner
- Institute of Physical and Theoretical Chemistry, and Center of Biomolecular Magnetic Resonance, Goethe University, Frankfurt am Main, Germany.
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11
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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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12
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Abstract
The DEER (double electron-electron resonance, also called PELDOR) experiment, which probes the dipolar interaction between two spins and thus reveals distance information, is an important tool for structural studies. In recent years, shaped pump pulses have become a valuable addition to the DEER experiment. Shaped pulses offer an increased excitation bandwidth and the possibility to precisely adjust pulse parameters, which is beneficial especially for demanding biological samples. We have noticed that on our home built W-band spectrometer, the dead-time free 4-pulse DEER sequence with chirped pump pulses suffers from distortions at the end of the DEER trace. Although minor, these are crucial for Gd(III)-Gd(III) DEER where the modulation depth is on the order of a few percent. Here we present a modified DEER sequence—referred to as reversed DEER (rDEER)—that circumvents the coherence pathway which gives rise to the distortion. We compare the rDEER (with two chirped pump pulses) performance values to regular 4-pulse DEER with one monochromatic as well as two chirped pulses and investigate the source of the distortion. We demonstrate the applicability and effectivity of rDEER on three systems, ubiquitin labeled with Gd(III)-DOTA-maleimide (DOTA, 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid) or with Gd(III)-DO3A (DO3A, 1,4,7,10-Tetraazacyclododecane-1,4,7-triyl) triacetic acid) and the multidrug transporter MdfA, labeled with a Gd(III)-C2 tag, and report an increase in the signal-to-noise ratio in the range of 3 to 7 when comparing the rDEER with two chirped pump pulses to standard 4-pulse DEER.
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Giannoulis A, Yang Y, Gong YJ, Tan X, Feintuch A, Carmieli R, Bahrenberg T, Liu Y, Su XC, Goldfarb D. DEER distance measurements on trityl/trityl and Gd(iii)/trityl labelled proteins. Phys Chem Chem Phys 2019; 21:10217-10227. [DOI: 10.1039/c8cp07249c] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Trityl–trityl and trityl–Gd(iii) DEER distance measurements in proteins are performed using a new trityl spin label affording thioether–protein conjugation.
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Affiliation(s)
- Angeliki Giannoulis
- Department of Chemical and Biological Physics
- Weizmann Institute of Science
- Rehovot 76100
- Israel
| | - Yin Yang
- Department of Chemical and Biological Physics
- Weizmann Institute of Science
- Rehovot 76100
- Israel
| | - Yan-Jun Gong
- State Key Laboratory of Elemento-organic Chemistry
- Collaborative Innovation Center of Chemical Science and Engineering
- Nankai University
- Tianjin 300071
- China
| | - Xiaoli Tan
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics
- School of Pharmacy
- Tianjin Medical University
- Tianjin 300070
- China
| | - Akiva Feintuch
- Department of Chemical and Biological Physics
- Weizmann Institute of Science
- Rehovot 76100
- Israel
| | - Raanan Carmieli
- Department of Chemical Research Support
- Weizmann Institute of Science
- Rehovot 76100
- Israel
| | - Thorsten Bahrenberg
- Department of Chemical and Biological Physics
- Weizmann Institute of Science
- Rehovot 76100
- Israel
| | - Yangping Liu
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics
- School of Pharmacy
- Tianjin Medical University
- Tianjin 300070
- China
| | - Xun-Cheng Su
- State Key Laboratory of Elemento-organic Chemistry
- Collaborative Innovation Center of Chemical Science and Engineering
- Nankai University
- Tianjin 300071
- China
| | - Daniella Goldfarb
- Department of Chemical and Biological Physics
- Weizmann Institute of Science
- Rehovot 76100
- Israel
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