142 results match your criteria Applied Magnetic Resonance[Journal]


Impact of Chlorine Substitution on Electron Spin Relaxation of a Trityl Radical.

Appl Magn Reson 2022 May 12;53(3-5):797-808. Epub 2021 Aug 12.

Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, USA.

A perchlorotriarylmethyl tricarboxylic acid radical 99% enriched in C at the central carbon (C-PTMTC) was characterized in phosphate buffered saline solution (pH = 7.2) (PBS) at ambient temperature. Samples immobilized in 1:1 PBS:glycerol or in 9:1 trehalose:sucrose were studied as a function of temperature. Read More

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Characterizing SPASM/twitch Domain-Containing Radical SAM Enzymes by EPR Spectroscopy.

Appl Magn Reson 2022 12;53(3-5):809-820. Epub 2021 Aug 12.

Department of Chemistry, University of California, Davis, CA 95616 USA.

Owing to their importance, diversity and abundance of generated paramagnetic species, radical -adenosylmethionine (rSAM) enzymes have become popular targets for electron paramagnetic resonance (EPR) spectroscopic studies. In contrast to prototypic single-domain and thus single-[4Fe-4S]-containing rSAM enzymes, there is a large subfamily of rSAM enzymes with multiple domains and one or two additional iron-sulfur cluster(s) called the SPASM/twitch domain-containing rSAM enzymes. EPR spectroscopy is a powerful tool that allows for the observation of the iron-sulfur clusters as well as potentially trappable paramagnetic reaction intermediates. Read More

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Rotational Coupling in Methyl-Tunneling Electron Spin Echo Envelope Modulation.

Authors:
Gunnar Jeschke

Appl Magn Reson 2022 14;53(3-5):635-651. Epub 2021 Jul 14.

Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland.

Coherence between tunnel-split states of a methyl quantum rotor can be generated and observed in stimulated and spin-locked echo experiments, if hyperfine coupling of a nearby electron spin to the methyl protons breaks C symmetry and is of the same order of magnitude as the tunnel splitting. Here, we consider the case of two methyl groups bound to the same sp -hybridized atom, which is important in the context of common nitroxide spin labels. For a simple form of the rotor-rotor coupling Hamiltonian, we provide an approach that allows for density operator computations of this system with 1152 quantum states with moderate computational effort. Read More

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Dispersion EPR: Considerations for Low-Frequency Experiments.

Appl Magn Reson 2022 Jan 29;53(1):193-206. Epub 2021 May 29.

Medical College of Wisconsin, Department of Biophysics, Milwaukee, WI, USA.

The hypothesis is made that the dispersion electron paramagnetic resonance (EPR) spectrum can yield a higher signal-to-noise ratio than the absorption spectrum in diagnostic examinations if phase noise in the bridge is under control. The rationale for this hypothesis is based on the observation that the dispersion spectrum becomes more intense than the absorption spectrum at high incident powers. The rationale is dependent on optimization of high microwave efficiency (Λ; mT/W) and low quality factor (Q-value) resonators as well as the use of microwave sources with reduced phase noise. Read More

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January 2022

Theory and Least Squares Fitting of CW ESR Saturation Spectra Using the MOMD Model.

Appl Magn Reson 2022 May 18;53(3-5):699-715. Epub 2021 Jul 18.

National Biomedical Center for Advanced ESR Technology and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.

CW saturation experiments are widely used in ESR studies of relaxation processes in proteins and lipids. We develop the theory of saturation in ESR spectra in terms of its close relation with that of 2D-ELDOR. Our treatment of saturation is then based on the microscopic order macroscopic disorder (MOMD) model and can be used to fit the full CW saturation spectrum, rather than fitting just the peak-peak amplitude as a function of microwave field as is commonly done. Read More

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The Fourth Konstantin Ivanov Intercontinental Magnetic Resonance Conference on Methods and Applications ICONS-4.

Appl Magn Reson 2022 24;53(6):857-860. Epub 2022 Mar 24.

TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research Hyderabad, 36/P Gopanpally Village, Ranga Reddy District, Hyderabad 500107 India.

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Autobiography.

Authors:
Kev M Salikhov

Appl Magn Reson 2022 23;53(3-5):491-520. Epub 2022 Mar 23.

Zavoisky Physical-Technical Institute, FRC Kazan Scientific Center of RAS, Kazan, 420029 Russia.

On the occasion of my 85th birthday, I share insights about my life and science. This autobiography has been written in an interesting period of my life. Two years ago I formulated a new paradigm in a particular scientific discipline: spin exchange. Read More

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A Review of Low-Frequency EPR Technology for the Measurement of Brain pO2 and Oxidative Stress.

Appl Magn Reson 2021 Oct 16;52(10):1379-1394. Epub 2021 Jul 16.

Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, NM 87131.

EPR can uniquely measure paramagnetic species. Although commercial EPR was introduced in 1950s, the early studies were mostly restricted to chemicals in solution or cellular experiments using X-band EPR equipment. Due to its limited penetration (<1 mm), experiments with living animals were almost impossible. Read More

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October 2021

H-HYSCORE Reveals Structural Details at the Fe(II) Active Site of Taurine:2-Oxoglutarate Dioxygenase.

Appl Magn Reson 2021 Aug 28;52(8):971-994. Epub 2020 Oct 28.

Departments of Biochemistry and Molecular Biology, and Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824.

Proton Hyperfine Sublevel Correlation (H-HYSCORE) experiments have been used to probe the ligation structure of the Fe(II) active site of taurine:2-oxoglutarate dioxygenase (TauD), a non-heme Fe(II) hydroxylase. To facilitate Electron Paramagnetic Resonance (EPR) experiments, Fe(II) derivatives of the enzyme were studied using nitric oxide as a substitute for molecular oxygen. The addition of NO to the enzyme yields an S = 3/2 {FeNO} paramagnetic center characterized by nearly axial EPR spectra with g = 4 and g = 2. Read More

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Special Issues of AMR on the Occasion of the 85th Birthday of Harold M. Swartz (HMS): Overview of Part 2 Articles and HMS' Citations on Magnetic Resonance.

Appl Magn Reson 2022 5;53(1):1-45. Epub 2022 Jan 5.

Biomedical Magnetic Resonance, Louvain Drug Research Institute, Université Catholique du Louvain, Brussels, Belgium.

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January 2022

Spin Labeling of Surface Cysteines Using a Bromoacrylaldehyde Spin Label.

Appl Magn Reson 2021 10;52(8):959-970. Epub 2021 Jun 10.

Centre for Natural Products Discovery, School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, L3 3AF UK.

Structural investigations of proteins and their biological complexes are now frequently complemented by distance constraints between spin labeled cysteines generated using double electron-electron resonance (DEER) spectroscopy, via site directed spin labeling (SDSL). Methanethiosulfonate spin label (MTSSL), has become ubiquitous in the SDSL of proteins, however, has limitations owing to its high number of rotamers, and reducibility. In this article we introduce the use of bromoacrylaldehyde spin label (BASL) as a cysteine spin label, demonstrating an advantage over MTSSL due to its increased selectivity for surface cysteines, eliminating the need to 'knock out' superfluous cysteine residues. Read More

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One Electron Multiple Proton Transfer in Model Organic Donor-Acceptor Systems: Implications for High Frequency EPR.

Appl Magn Reson 2020 Oct 1;51(9-10):977-991. Epub 2020 Oct 1.

Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, USA.

EPR spectroscopy is an important spectroscopic method for identification and characterization of radical species involved in many biological reactions. The tyrosyl radical is one of the most studied amino acid radical intermediates in biology. Often in conjunction with histidine residues, it is involved in many fundamental biological electron and proton transfer processes, such as in the water oxidation in photosystem II. Read More

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October 2020

Evaluation of a Refined Implantable Resonator for Deep-Tissue EPR Oximetry in the Clinic.

Appl Magn Reson 2021 Oct 9;52(10):1321-1342. Epub 2021 Jul 9.

Department of Radiology, Geisel School of Medicine at Dartmouth, Hanover, NH, United States.

Objectives: (1) Summarize revisions made to the implantable resonator (IR) design and results of testing to characterize biocompatibility;(2) Demonstrate safety of implantation and feasibility of deep tissue oxygenation measurement using electron paramagnetic resonance (EPR) oximetry.

Study Design: In vitro testing of the revised IR and in vivo implantation in rabbit brain and leg tissues.

Methods: Revised IRs were fabricated with 1-4 OxyChips with a thin wire encapsulated with two biocompatible coatings. Read More

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October 2021

DEER and RIDME Measurements of the Nitroxide-Spin Labelled Copper-Bound Amine Oxidase Homodimer from Arthrobacter Globiformis.

Appl Magn Reson 2021 29;52(8):995-1015. Epub 2021 Mar 29.

SUPA School of Physics and Astronomy and BSRC, University of St Andrews, St Andrews, KY16 9SS UK.

In the study of biological structures, pulse dipolar spectroscopy (PDS) is used to elucidate spin-spin distances at nanometre-scale by measuring dipole-dipole interactions between paramagnetic centres. The PDS methods of Double Electron Electron Resonance (DEER) and Relaxation Induced Dipolar Modulation Enhancement (RIDME) are employed, and their results compared, for the measurement of the dipolar coupling between nitroxide spin labels and copper-II (Cu(II)) paramagnetic centres within the copper amine oxidase from (AGAO). The distance distribution results obtained indicate that two distinct distances can be measured, with the longer of these at c. Read More

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The Third Konstantin Ivanov Intercontinental Magnetic Resonance Conference on Methods and Applications ICONS-3.

Appl Magn Reson 2021 24;52(11):1537-1541. Epub 2021 Oct 24.

TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research Hyderabad, 36/P Gopanpally Village, Ranga Reddy District, Hyderabad, 500107 India.

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October 2021

The Interaction of Water-Soluble Nitroxide Radicals with Photosystem II.

Appl Magn Reson 2021 Sep 9:1-15. Epub 2021 Sep 9.

Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow, Russia.

In this work, we investigated the redox transients of a number of water-soluble spin labels upon their interactions with Photosystem II (PS II) core complexes isolated from spinach leaves. We have found that the reactivity of nitroxide radicals, determined by the rate of their reduction upon illumination of PS II, depends on the chemical structure of radicals and the capability of their coming close to low-potential redox centers of photoactive PS II complexes. An enhanced capability of nitroxide radicals to accept electrons from PS II correlates with their chemical structure. Read More

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September 2021

Multinuclear MRI Research.

Authors:
Yu A Pirogov

Appl Magn Reson 2021 31;52(12):1695-1705. Epub 2021 Jul 31.

Faculty of Physics, M. V. Lomonosov Moscow State University, Moscow, Russia.

The presented data clearly demonstrate that multinuclear MRI has a great potential in research and clinical fields. The biomedical value of many heavy nuclei that are part of drugs, contrast agents, and molecular complexes in live tissues emphasizes the need for creating and using MRI scanners tuned to the Larmor frequencies of such nuclei. This article discusses a number of specific problems solved with the use of multinuclear MRI. Read More

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Gareth R. Eaton: On the Occasion of His 80th Birthday.

Appl Magn Reson 2021 27;52(8):903-905. Epub 2021 Jul 27.

West Virginia University, Morgantown, West Virginia USA.

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Electron Spin Relaxation of Tb and Tm Ions.

Appl Magn Reson 2020 Oct 14;51(9-10):961-976. Epub 2020 Sep 14.

Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA.

Electron spin relaxation times T and T of Tb and Tm in 1:1 water:ethanol and of Tb doped (2%) in crystalline La(oxalate) decahydrate were measured between about 4.2 and 10 K. Both cations are non-Kramers ions and have J = 6 ground states. Read More

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October 2020

Editorial: The Second Intercontinental NMR Conference ICONS2021.

Appl Magn Reson 2021 17;52(5):565-569. Epub 2021 Apr 17.

TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research Hyderabad, 36/P Gopanpally Village, Ranga Reddy District, Hyderabad, 500107 India.

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Photo-CIDNP in Solid State.

Appl Magn Reson 2022 6;53(3-5):521-537. Epub 2021 Apr 6.

Institut für Medizinische Physik und Biophysik, Universität Leipzig, Härtelstr. 16-18, 04107 Leipzig, Germany.

Photo-CIDNP (photo-chemically induced dynamic nuclear polarization) refers to nuclear polarization created by the spin-chemical evolution of spin-correlated radical pairs (SCRPs). This phenomenon occurs in gases, liquids and solids. Based on the solid-state photo-CIDNP effect observed under magic-angle spinning (MAS), photo-CIDNP MAS NMR has been developed as analytical method. Read More

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Oxygen Transport Parameter in Plasma Membrane of Eye Lens Fiber Cells by Saturation Recovery EPR.

Appl Magn Reson 2021 Jan 14;52(1):61-80. Epub 2020 Aug 14.

Department of Biophysics, Medical College of Wisconsin, Milwaukee, USA.

A probability distribution of rate constants contained within an exponential-like saturation recovery (SR) electron paramagnetic resonance signal can be constructed using stretched exponential function fitting parameters. Previously (Stein et al. 2019. Read More

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January 2021

Going Low in a World Going High: The Physiologic Use of Lower Frequency Electron Paramagnetic Resonance.

Appl Magn Reson 2020 Oct 18;51(9-10):887-907. Epub 2020 Oct 18.

Center for EPR imaging in vivo physiology, University of Chicago.

Yakov Sergeevich Lebedev was a pioneer in high frequency EPR, taking advantage of the separation of g-factor anisotropy effects from nuclear hyperfine splitting and the higher frequency molecular motion sensitivity from higher frequency measurements. This article celebrates a second EPR subfield in which Prof. Lebedev pioneered, EPR imaging. Read More

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October 2020

Carotenoids: Importance in Daily Life-Insight Gained from EPR and ENDOR.

Appl Magn Reson 2021 20;52(8):1093-1112. Epub 2021 Mar 20.

Department of Chemistry, The University of Alabama, Box 870336, Tuscaloosa, AL 35487 USA.

Carotenoids are indispensable molecules for life. They are present everywhere in plants, algae, bacteria whom they protect against free radicals and oxidative stress. Through the consumption of fruits and vegetables and some carotenoid-containing fish, they are introduced into the human body and, similarly, protect it. Read More

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Rapid Scan EPR imaging as a Tool for Magnetic Field Mapping.

Appl Magn Reson 2020 Oct 25;51(9-10):1117-1124. Epub 2020 Sep 25.

Department of Biochemistry, West Virginia University, Morgantown, WV 26506, USA.

Functional four-dimensional spectral-spatial electron paramagnetic imaging (EPRI) is routinely used in biomedical research. Positions and widths of EPR lines in the spectral dimension report oxygen partial pressure, pH, and other important parameters of the tissue microenvironment. Images are measured in the homogeneous external magnetic field. Read More

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October 2020

EPR Everywhere.

Appl Magn Reson 2021 24;52(8):1113-1139. Epub 2021 Jan 24.

University of Denver, Denver, CO 80210 USA.

This review is inspired by the contributions from the University of Denver group to low-field EPR, in honor of Professor Gareth Eaton's 80th birthday. The goal is to capture the spirit of innovation behind the body of work, especially as it pertains to development of new EPR techniques. The spirit of the DU EPR laboratory is one that never sought to limit what an EPR experiment could be, or how it could be applied. Read More

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January 2021

Applied Magnetic Resonance Under Conditions of a Pandemic.

Appl Magn Reson 2020 22;51(12):1621-1624. Epub 2020 Oct 22.

Kazan Federal University, Kazan, Russia.

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October 2020

How is Nitric Oxide (NO) Converted into Nitrosonium Cations (NO) in Living Organisms? (Based on the Results of Optical and EPR Analyses of Dinitrosyl Iron Complexes with Thiol-Containing Ligands).

Authors:
Anatoly F Vanin

Appl Magn Reson 2020 20;51(9-10):851-876. Epub 2020 Oct 20.

Semenov Federal Research Center of Chemical Physics, Russian Academy of Sciences, Moscow, Russia.

The present work provides theoretical and experimental foundations for the ability of dinitrosyl iron complexes (DNICs) with thiolcontaining ligands to be not only the donors of neutral NO molecules, but also the donors of nitrosonium cations (NO) in living organisms ensuring S-nitrosation of various proteins and low-molecular-weight compounds. It is proposed that the emergence of those cations in DNICs is related to disproportionation reaction of NO molecules, initiated by their binding with Fe ions (two NO molecules per one ion). At the same time, possible hydrolysis of iron-bound nitrosonium cations is prevented by the electron density transition to nitrosonium cations from sulfur atoms of thiol-containing ligands, which are included in the coordination sphere of iron. Read More

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October 2020

Dante Gatteschi: on the Occasion of His 75th Birthday.

Appl Magn Reson 2020 13;51(11):1211-1213. Epub 2020 Oct 13.

Department of Chemical Sciences, University of Padova, via Marzolo 1, Padova, Italy.

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October 2020

Editorial: Introducing the Intercontinental NMR Seminar ICONS2020.

Appl Magn Reson 2021 12;52(1):1-4. Epub 2020 Oct 12.

TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research Hyderabad, 36/P Gopanpally Village, Ranga Reddy District, Hyderabad, 500107 India.

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October 2020