1
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Grosskopf JD, Sidabras JW, Altenbach C, Anderson JR, Mett RR, Strangeway RA, Hyde JS, Hubbell WL, Lerch MT. A pressure-jump EPR system to monitor millisecond conformational exchange rates of spin-labeled proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.07.593074. [PMID: 38766191 PMCID: PMC11100676 DOI: 10.1101/2024.05.07.593074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Site-directed spin labeling electron paramagnetic resonance (SDSL-EPR) using nitroxide spin labels is a well-established technology for mapping site-specific secondary and tertiary structure and for monitoring conformational changes in proteins of any degree of complexity, including membrane proteins, with high sensitivity. SDSL-EPR also provides information on protein dynamics in the time scale of ps-µs using continuous wave lineshape analysis and spin lattice relaxation time methods. However, the functionally important time domain of µs-ms, corresponding to large-scale protein motions, is inaccessible to those methods. To extend SDSL-EPR to the longer time domain, the perturbation method of pressure-jump relaxation is implemented. Here, we describe a complete high-pressure EPR system at Q-band for both static pressure and millisecond-timescale pressure-jump measurements on spin-labeled proteins. The instrument enables pressure jumps both up and down from any holding pressure, ranging from atmospheric pressure to the maximum pressure capacity of the system components (~3500 bar). To demonstrate the utility of the system, we characterize a local folding-unfolding equilibrium of T4 lysozyme. The results illustrate the ability of the system to measure thermodynamic and kinetic parameters of protein conformational exchange on the millisecond timescale.
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Affiliation(s)
- Julian D Grosskopf
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Jason W Sidabras
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Christian Altenbach
- Department of Chemistry and Biochemistry and Stein Eye Institute, University of California, Los Angeles, CA 90095, USA
| | - Jim R Anderson
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Richard R Mett
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Robert A Strangeway
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - James S Hyde
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Wayne L Hubbell
- Department of Chemistry and Biochemistry and Stein Eye Institute, University of California, Los Angeles, CA 90095, USA
| | - Michael T Lerch
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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2
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Bartoš J, Švajdlenková H. Thermodynamic and Dynamic Transitions and Interaction Aspects in Reorientation Dynamics of Molecular Probe in Organic Compounds: A Series of 1-alkanols with TEMPO. Int J Mol Sci 2023; 24:14252. [PMID: 37762553 PMCID: PMC10532429 DOI: 10.3390/ijms241814252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 09/08/2023] [Accepted: 09/09/2023] [Indexed: 09/29/2023] Open
Abstract
The spectral and dynamic properties of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) in a series of 1-alkanols ranging from methanol to 1-decanol over a temperature range 100-300 K were investigated by electron spin resonance (ESR). The main characteristic ESR temperatures connected with slow to fast motion regime transition; T50G 's and TX1fast 's are situated above the corresponding glass temperatures, Tg, and for the shorter members, the T50G 's lie above or close to melting point, Tm, while the longer ones the T50G < Tm relationship indicates that the TEMPO molecules are in the local disordered regions of the crystalline media. The T50G 's and especially TX1fast 's are compared with the dynamic crossover temperatures, TXVISC = 8.72M0.66, as obtained by fitting the viscosity data in the liquid n-alkanols with the empirical power law. In particular, for NC > 6, the TX1fast 's lie rather close to the TXVISC resembling apolar n-alkanes [PCCP 2018,20,11145-11151], while for NC < 6, they are situated in the vicinity of Tm. The absence of a coincidence for lower1-alkanols indicates that the T50G is significantly influenced by the mutual interaction between the polar TEMPO and the protic polar medium due to the increased polarity and proticity destroyed by the larger-scale melting transition.
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Affiliation(s)
- Josef Bartoš
- Polymer Institute of SAS, 845 41 Bratislava, Slovakia;
| | - Helena Švajdlenková
- Polymer Institute of SAS, 845 41 Bratislava, Slovakia;
- Department of Nuclear Chemistry, Faculty of Natural Sciences, Comenius University, 842 15 Bratislava, Slovakia
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3
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Tran VA, Teucher M, Galazzo L, Sharma B, Pongratz T, Kast SM, Marx D, Bordignon E, Schnegg A, Neese F. Dissecting the Molecular Origin of g-Tensor Heterogeneity and Strain in Nitroxide Radicals in Water: Electron Paramagnetic Resonance Experiment versus Theory. J Phys Chem A 2023; 127:6447-6466. [PMID: 37524058 PMCID: PMC10424240 DOI: 10.1021/acs.jpca.3c02879] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 07/01/2023] [Indexed: 08/02/2023]
Abstract
Nitroxides are common EPR sensors of microenvironmental properties such as polarity, numbers of H-bonds, pH, and so forth. Their solvation in an aqueous environment is facilitated by their high propensity to form H-bonds with the surrounding water molecules. Their g- and A-tensor elements are key parameters to extracting the properties of their microenvironment. In particular, the gxx value of nitroxides is rich in information. It is known to be characterized by discrete values representing nitroxide populations previously assigned to have different H-bonds with the surrounding waters. Additionally, there is a large g-strain, that is, a broadening of g-values associated with it, which is generally correlated with environmental and structural micro-heterogeneities. The g-strain is responsible for the frequency dependence of the apparent line width of the EPR spectra, which becomes evident at high field/frequency. Here, we address the molecular origin of the gxx heterogeneity and of the g-strain of a nitroxide moiety (HMI: 2,2,3,4,5,5-hexamethylimidazolidin-1-oxyl, C9H19N2O) in water. To treat the solvation effect on the g-strain, we combined a multi-frequency experimental approach with ab initio molecular dynamics simulations for structural sampling and quantum chemical EPR property calculations at the highest realistically affordable level, including an explicitly micro-solvated HMI ensemble and the embedded cluster reference interaction site model. We could clearly identify the distinct populations of the H-bonded nitroxides responsible for the gxx heterogeneity experimentally observed, and we dissected the role of the solvation shell, H-bond formation, and structural deformation of the nitroxide in the creation of the g-strain associated with each nitroxide subensemble. Two contributions to the g-strain were identified in this study. The first contribution depends on the number of hydrogen bonds formed between the nitroxide and the solvent because this has a large and well-understood effect on the gxx-shift. This contribution can only be resolved at high resonance frequencies, where it leads to distinct peaks in the gxx region. The second contribution arises from configurational fluctuations of the nitroxide that necessarily lead to g-shift heterogeneity. These contributions cannot be resolved experimentally as distinct resonances but add to the line broadening. They can be quantitatively analyzed by studying the apparent line width as a function of microwave frequency. Interestingly, both theory and experiment confirm that this contribution is independent of the number of H-bonds. Perhaps even more surprisingly, the theoretical analysis suggests that the configurational fluctuation broadening is not induced by the solvent but is inherently present even in the gas phase. Moreover, the calculations predict that this broadening decreases upon solvation of the nitroxide.
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Affiliation(s)
- Van Anh Tran
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Markus Teucher
- Max-Planck-Institut
für Chemische Energiekonversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Laura Galazzo
- Department
of Physical Chemistry, University of Geneva, Quai Ernest Ansermet 30, 1211 Geneva, Switzerland
- Faculty
of Chemistry and Biochemistry, Ruhr-Universität
Bochum, 44780 Bochum, Germany
| | - Bikramjit Sharma
- Lehrstuhl
für Theoretische Chemie, Ruhr-Universität
Bochum, 44780 Bochum, Germany
| | - Tim Pongratz
- Fakultät
für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 4a, 44227 Dortmund, Germany
| | - Stefan M. Kast
- Fakultät
für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 4a, 44227 Dortmund, Germany
| | - Dominik Marx
- Lehrstuhl
für Theoretische Chemie, Ruhr-Universität
Bochum, 44780 Bochum, Germany
| | - Enrica Bordignon
- Department
of Physical Chemistry, University of Geneva, Quai Ernest Ansermet 30, 1211 Geneva, Switzerland
- Faculty
of Chemistry and Biochemistry, Ruhr-Universität
Bochum, 44780 Bochum, Germany
| | - Alexander Schnegg
- Max-Planck-Institut
für Chemische Energiekonversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Frank Neese
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
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4
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Szczuka C, Eichel RA, Granwehr J. Gauging the importance of structural parameters for hyperfine coupling constants in organic radicals. RSC Adv 2023; 13:14565-14574. [PMID: 37188254 PMCID: PMC10177955 DOI: 10.1039/d3ra02476h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 05/08/2023] [Indexed: 05/17/2023] Open
Abstract
The identification of fundamental relationships between atomic configuration and electronic structure typically requires experimental empiricism or systematic theoretical studies. Here, we provide an alternative statistical approach to gauge the importance of structure parameters, i.e., bond lengths, bond angles, and dihedral angles, for hyperfine coupling constants in organic radicals. Hyperfine coupling constants describe electron-nuclear interactions defined by the electronic structure and are experimentally measurable, for example, by electron paramagnetic resonance spectroscopy. Importance quantifiers are computed with the machine learning algorithm neighborhood components analysis using molecular dynamics trajectory snapshots. Atomic-electronic structure relationships are visualized in matrices correlating structure parameters with coupling constants of all magnetic nuclei. Qualitatively, the results reproduce common hyperfine coupling models. Tools to use the presented procedure for other radicals/paramagnetic species or other atomic structure-dependent parameters are provided.
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Affiliation(s)
- Conrad Szczuka
- Institute of Energy and Climate Research (IEK-9), Forschungszentrum Jülich GmbH 52425 Jülich Germany
| | - Rüdiger-A Eichel
- Institute of Energy and Climate Research (IEK-9), Forschungszentrum Jülich GmbH 52425 Jülich Germany
- Institute of Physical Chemistry, RWTH Aachen University 52056 Aachen Germany
| | - Josef Granwehr
- Institute of Energy and Climate Research (IEK-9), Forschungszentrum Jülich GmbH 52425 Jülich Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University 52056 Aachen Germany
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5
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Galazzo L, Bordignon E. Electron paramagnetic resonance spectroscopy in structural-dynamic studies of large protein complexes. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2023; 134-135:1-19. [PMID: 37321755 DOI: 10.1016/j.pnmrs.2022.11.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 11/11/2022] [Accepted: 11/17/2022] [Indexed: 06/17/2023]
Abstract
Macromolecular protein assemblies are of fundamental importance for many processes inside the cell, as they perform complex functions and constitute central hubs where reactions occur. Generally, these assemblies undergo large conformational changes and cycle through different states that ultimately are connected to specific functions further regulated by additional small ligands or proteins. Unveiling the 3D structural details of these assemblies at atomic resolution, identifying the flexible parts of the complexes, and monitoring with high temporal resolution the dynamic interplay between different protein regions under physiological conditions is key to fully understanding their properties and to fostering biomedical applications. In the last decade, we have seen remarkable advances in cryo-electron microscopy (EM) techniques, which deeply transformed our vision of structural biology, especially in the field of macromolecular assemblies. With cryo-EM, detailed 3D models of large macromolecular complexes in different conformational states became readily available at atomic resolution. Concomitantly, nuclear magnetic resonance (NMR) and electron paramagnetic resonance spectroscopy (EPR) have benefited from methodological innovations which also improved the quality of the information that can be achieved. Such enhanced sensitivity widened their applicability to macromolecular complexes in environments close to physiological conditions and opened a path towards in-cell applications. In this review we will focus on the advantages and challenges of EPR techniques with an integrative approach towards a complete understanding of macromolecular structures and functions.
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Affiliation(s)
- Laura Galazzo
- Department of Physical Chemistry, University of Geneva, Quai Ernest Ansermet 30, CH-1211 Genève 4, Switzerland.
| | - Enrica Bordignon
- Department of Physical Chemistry, University of Geneva, Quai Ernest Ansermet 30, CH-1211 Genève 4, Switzerland.
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6
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Rančić A, Babić N, Orio M, Peyrot F. Structural Features Governing the Metabolic Stability of Tetraethyl-Substituted Nitroxides in Rat Liver Microsomes. Antioxidants (Basel) 2023; 12:antiox12020402. [PMID: 36829960 PMCID: PMC9952648 DOI: 10.3390/antiox12020402] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 01/30/2023] [Accepted: 02/01/2023] [Indexed: 02/11/2023] Open
Abstract
Nitroxides are potent tools for studying biological systems by electron paramagnetic resonance (EPR). Whatever the application, a certain stability is necessary for successful detection. Since conventional tetramethyl-substituted cyclic nitroxides have insufficient in vivo stability, efforts have recently been made to synthesize more stable, tetraethyl-substituted nitroxides. In our previous study on piperidine nitroxides, the introduction of steric hindrance around the nitroxide moiety successfully increased the resistance to reduction into hydroxylamine. However, it also rendered the carbon backbone susceptible to modifications by xenobiotic metabolism due to increased lipophilicity. Here, we focus on a new series of three nitroxide candidates with tetraethyl substitution, namely with pyrrolidine, pyrroline, and isoindoline cores, to identify which structural features afford increased stability for future probe design and application in in vivo EPR imaging. In the presence of rat liver microsomes, pyrrolidine and pyrroline tetraethyl nitroxides exhibited a higher stability than isoindoline nitroxide, which was studied in detail by HPLC-HRMS. Multiple metabolites suggest that the aerobic transformation of tetraethyl isoindoline nitroxide is initiated by hydrogen abstraction by P450-FeV = O from one of the ethyl groups, followed by rearrangement and further modifications by cytochrome P450, as supported by DFT calculations. Under anaerobic conditions, only reduction by rat liver microsomes was observed with involvement of P450-FeII.
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Affiliation(s)
- Aleksandra Rančić
- Laboratoire de Chimie et de Biochimie Pharmacologiques et Toxicologiques, Université Paris Cité, CNRS, F-75006 Paris, France
| | - Nikola Babić
- Laboratoire de Chimie et de Biochimie Pharmacologiques et Toxicologiques, Université Paris Cité, CNRS, F-75006 Paris, France
| | - Maylis Orio
- iSm2, Aix-Marseille University, CNRS, Centrale Marseille, F-13397 Marseille, France
| | - Fabienne Peyrot
- Laboratoire de Chimie et de Biochimie Pharmacologiques et Toxicologiques, Université Paris Cité, CNRS, F-75006 Paris, France
- Institut National Supérieur du Professorat et de l’Education (INSPE) de l’Académie de Paris, Sorbonne Université, F-75016 Paris, France
- Correspondence:
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7
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Hecker F, Fries L, Hiller M, Chiesa M, Bennati M. 17 O Hyperfine Spectroscopy Reveals Hydration Structure of Nitroxide Radicals in Aqueous Solutions. Angew Chem Int Ed Engl 2023; 62:e202213700. [PMID: 36399425 PMCID: PMC10107301 DOI: 10.1002/anie.202213700] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Revised: 11/14/2022] [Accepted: 11/17/2022] [Indexed: 11/19/2022]
Abstract
The hydration structure of nitroxide radicals in aqueous solutions is elucidated by advanced 17 O hyperfine (hf) spectroscopy with support of quantum chemical calculations and MD simulations. A piperidine and a pyrrolidine-based nitroxide radical are compared and show clear differences in the preferred directionality of H-bond formation. We demonstrate that these scenarios are best represented in 17 O hf spectra, where in-plane coordination over σ ${\sigma }$ -type H-bonding leads to little spin density transfer on the water oxygen and small hf couplings, whereas π ${{\rm \pi }}$ -type perpendicular coordination generates much larger hf couplings. Quantitative analysis of the spectra based on MD simulations and DFT predicted hf parameters is consistent with a distribution of close solvating water molecules, in which directionality is influenced by subtle steric effects of the ring and the methyl group substituents.
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Affiliation(s)
- Fabian Hecker
- Research Group EPR spectroscopy, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077, Göttingen, Germany
| | - Lisa Fries
- Research Group EPR spectroscopy, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077, Göttingen, Germany.,Current address: Center for Biostructural Imaging of Neurodegeneration, Medical Center Göttingen, Von-Siebold-Straße 3a, 37075, Göttingen, Germany.,NMR Signal Enhancement Group, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077, Göttingen, Germany
| | - Markus Hiller
- Research Group EPR spectroscopy, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077, Göttingen, Germany.,Current address: Isotope Technologies Dresden, Rossendorfer Ring 42, 01328, Dresden, Germany
| | - Mario Chiesa
- Department of Chemistry, University of Torino, Via Giuria 9, 10125, Torino, Italy
| | - Marina Bennati
- Research Group EPR spectroscopy, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077, Göttingen, Germany.,Department of Chemistry, Georg August University Göttingen, Tammanstrasse 2, 37077, Göttingen, Germany
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8
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Bartoš J, Vyroubalová M, Švajdlenková H. Bulk and confined acetonitrile in mesoporous silica matrices by extrinsic probing via ESR technique: Effects of pore topology, pore size and pore surface composition. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.140073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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9
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Weiß N, Thielemann G, Nagel K, Schmidt CH, Seifert A, Kaßner L, Strehmel V, Corzilius B, Schröder C, Spange S. The influence of the cation structure on the basicity-related polarity of ionic liquids. Phys Chem Chem Phys 2021; 23:26750-26760. [PMID: 34846390 DOI: 10.1039/d1cp03986e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
UV/Vis absorption data of (E)-4-(2-[5-{4,4,5,5-tetramethyl-1,3,2-dioxaborolane-2-yl}thiene-2-yl]vinyl)-2-(dicyano-methylene)-3-cyano-5,5-dimethyl-2,5-dihydrofuran (ThTCF) as a solvatochromic probe is applied to examine the anion coordination strength (e.g. of N(CN)2, BF4, PF6, N(Tf)2, CF3COO) as a function of the cation structure of ionic liquids. Several 1-n-alky-3-methylimidazolium- and tetraalkylammonium CH3-NR3+-based ILs with different n-alkyl chain lengths (R = -C4H9, -C6H11, -C8H17, -C10H21) are considered. UV/Vis absorption data of ThTCF show subtle correlations with hydrogen bond accepting (HBA) ability-related measurands such as Kamlet-Taft β, Freire's EHB, and Laurence β1 parameter as a function of anion and cation structure. The different influence of the n-alkyl chain length of imidazolium- and tetraalkylammonium-based ILs on the dipolarity and HBA strength is confirmed by comparison with the 14N isotropic hyperfine coupling constants (Aiso) of a positively (CATI) and negatively charged spin probe (TSKCr) of TEMPO-type [(2,2,6,6-tetramethylpiperidin-1-yl)oxyl] and quantum chemically derived dipoles of the cations. The Aiso values correlate with the absorption energy of ThTCF and EHB, but in different ways depending on the anion or charge of the spin probe. In a final discussion of the β, EHB, and β1 scales in relation to ThTCF, the importance of the molar concentration N of ionic liquids for the physical significance of the respective parameters is discussed.
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Affiliation(s)
- Nadine Weiß
- Department of Polymer Chemistry, Institute of Chemistry, Chemnitz University of Technology, Straße der Nationen 62, 09111 Chemnitz, Germany.
| | - Gabi Thielemann
- Department of Polymer Chemistry, Institute of Chemistry, Chemnitz University of Technology, Straße der Nationen 62, 09111 Chemnitz, Germany.
| | - Kevin Nagel
- Department of Polymer Chemistry, Institute of Chemistry, Chemnitz University of Technology, Straße der Nationen 62, 09111 Chemnitz, Germany.
| | - Caroline H Schmidt
- Department of Polymer Chemistry, Institute of Chemistry, Chemnitz University of Technology, Straße der Nationen 62, 09111 Chemnitz, Germany.
| | - Andreas Seifert
- Department of Polymer Chemistry, Institute of Chemistry, Chemnitz University of Technology, Straße der Nationen 62, 09111 Chemnitz, Germany.
| | - Lysann Kaßner
- Department of Polymer Chemistry, Institute of Chemistry, Chemnitz University of Technology, Straße der Nationen 62, 09111 Chemnitz, Germany.
| | - Veronika Strehmel
- Department of Chemistry, Organic Chemistry and Institute for Coatings and Surface Chemistry, Hochschule Niederrhein, University of Applied Sciences, Adlerstraße 32, 47798 Krefeld, Germany.
| | - Björn Corzilius
- Institute of Chemistry, University Rostock, Albert-Einstein-Str. 3a, 18059 Rostock, Germany.
| | - Christian Schröder
- Institute of Computational Biological Chemistry, University of Vienna, Währingerstr. 17, 1090 Vienna, Austria.
| | - Stefan Spange
- Department of Polymer Chemistry, Institute of Chemistry, Chemnitz University of Technology, Straße der Nationen 62, 09111 Chemnitz, Germany.
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10
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Sharma B, Tran VA, Pongratz T, Galazzo L, Zhurko I, Bordignon E, Kast SM, Neese F, Marx D. A Joint Venture of Ab Initio Molecular Dynamics, Coupled Cluster Electronic Structure Methods, and Liquid-State Theory to Compute Accurate Isotropic Hyperfine Constants of Nitroxide Probes in Water. J Chem Theory Comput 2021; 17:6366-6386. [PMID: 34516119 PMCID: PMC8515807 DOI: 10.1021/acs.jctc.1c00582] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Indexed: 01/11/2023]
Abstract
The isotropic hyperfine coupling constant (HFCC, Aiso) of a pH-sensitive spin probe in a solution, HMI (2,2,3,4,5,5-hexamethylimidazolidin-1-oxyl, C9H19N2O) in water, is computed using an ensemble of state-of-the-art computational techniques and is gauged against X-band continuous wave electron paramagnetic resonance (EPR) measurement spectra at room temperature. Fundamentally, the investigation aims to delineate the cutting edge of current first-principles-based calculations of EPR parameters in aqueous solutions based on using rigorous statistical mechanics combined with correlated electronic structure techniques. In particular, the impact of solvation is described by exploiting fully atomistic, RISM integral equation, and implicit solvation approaches as offered by ab initio molecular dynamics (AIMD) of the periodic bulk solution (using the spin-polarized revPBE0-D3 hybrid functional), embedded cluster reference interaction site model integral equation theory (EC-RISM), and polarizable continuum embedding (using CPCM) of microsolvated complexes, respectively. HFCCs are obtained from efficient coupled cluster calculations (using open-shell DLPNO-CCSD theory) as well as from hybrid density functional theory (using revPBE0-D3). Re-solvation of "vertically desolvated" spin probe configuration snapshots by EC-RISM embedding is shown to provide significantly improved results compared to CPCM since only the former captures the inherent structural heterogeneity of the solvent close to the spin probe. The average values of the Aiso parameter obtained based on configurational statistics using explicit water within AIMD and from EC-RISM solvation are found to be satisfactorily close. Using either such explicit or RISM solvation in conjunction with DLPNO-CCSD calculations of the HFCCs provides an average Aiso parameter for HMI in aqueous solution at 300 K and 1 bar that is in good agreement with the experimentally determined one. The developed computational strategy is general in the sense that it can be readily applied to other spin probes of similar molecular complexity, to aqueous solutions beyond ambient conditions, as well as to other solvents in the longer run.
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Affiliation(s)
- Bikramjit Sharma
- Lehrstuhl
für Theoretische Chemie, Ruhr-Universität
Bochum, 44780 Bochum, Germany
| | - Van Anh Tran
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Tim Pongratz
- Physikalische
Chemie III, Technische Universität
Dortmund, Otto-Hahn-Str. 4a, 44227 Dortmund, Germany
| | - Laura Galazzo
- Faculty
of Chemistry and Biochemistry, Ruhr University
Bochum, 44780 Bochum, Germany
| | - Irina Zhurko
- Laboratory
of Nitrogen Compounds, N.N. Vorozhtsov Novosibirsk Institute of Organic
Chemistry, NIOCH SB RAS, 9 Lavrentiev Avenue, 630090, Novosibirsk, Russia
| | - Enrica Bordignon
- Faculty
of Chemistry and Biochemistry, Ruhr University
Bochum, 44780 Bochum, Germany
| | - Stefan M. Kast
- Physikalische
Chemie III, Technische Universität
Dortmund, Otto-Hahn-Str. 4a, 44227 Dortmund, Germany
| | - Frank Neese
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Dominik Marx
- Lehrstuhl
für Theoretische Chemie, Ruhr-Universität
Bochum, 44780 Bochum, Germany
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11
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Bachman BF, Jones ZR, Jaffe GR, Salman J, Wambold R, Yu Z, Choy JT, Kolkowitz SJ, Eriksson MA, Kats MA, Hamers RJ. High-Density Covalent Grafting of Spin-Active Molecular Moieties to Diamond Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:9222-9231. [PMID: 34279965 DOI: 10.1021/acs.langmuir.1c01425] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Functionalization of diamond surfaces with TEMPO and other surface paramagnetic species represents one approach to the implementation of novel chemical detection schemes that make use of shallow quantum color defects such as silicon-vacancy (SiV) and nitrogen-vacancy (NV) centers. Yet, prior approaches to quantum-based chemical sensing have been hampered by the absence of high-quality surface functionalization schemes for linking radicals to diamond surfaces. Here, we demonstrate a highly controlled approach to the functionalization of diamond surfaces with carboxylic acid groups via all-carbon tethers of different lengths, followed by covalent chemistry to yield high-quality, TEMPO-modified surfaces. Our studies yield estimated surface densities of 4-amino-TEMPO of approximately 1.4 molecules nm-2 on nanodiamond (varying with molecular linker length) and 3.3 molecules nm-2 on planar diamond. These values are higher than those reported previously using other functionalization methods. The ζ-potential of nanodiamonds was used to track reaction progress and elucidate the regioselectivity of the reaction between ethenyl and carboxylate groups and surface radicals.
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Affiliation(s)
| | | | | | - Jad Salman
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, Wisconsin 53706, United States
| | - Raymond Wambold
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, Wisconsin 53706, United States
| | - Zhaoning Yu
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, Wisconsin 53706, United States
| | - Jennifer T Choy
- Department of Engineering Physics, University of Wisconsin-Madison, 1500 Engineering Drive, Madison, Wisconsin 53706, United States
| | | | | | - Mikhail A Kats
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, Wisconsin 53706, United States
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Zagrean-Tuza C, Mot AC, Chmiel T, Bende A, Turcu I. Sugar matters: sugar moieties as reactivity-tuning factors in quercetin O-glycosides. Food Funct 2021; 11:5293-5307. [PMID: 32458896 DOI: 10.1039/d0fo00319k] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Quercetin, one of the most abundant flavonoids in plant-based foods, commonly occurs in nature in various glycosylated forms. There is still a less explored aspect regarding the cause of diversity of its glycosides, depending on the sugar moiety attached. This work focuses on four wide-spread quercetin glycosides-hyperoside, isoquercitrin, quercitrin and rutin-by testing the property-tuning capacity of different sugar moieties and thus explains and predicts some of their functions in plant-based foods. The electron paramagnetic spectra of the semiquinone anion radicals of these glycosides were interpreted in terms of hyperfine coupling constants and linewidths, highlighting a clear link between spin density trends, the identity of the bound sugar, and their reactivity corroborated with their modelled structures. Redox potential and lipophilicity were connected to a specific flavonoid-enzyme interaction and correlated with their prooxidant reactivity assessed by oxidation of ferrous hemoglobin. Hyperoside and isoquercitin-galactose and glucose glycosides-exhibit the highest prooxidant reactivity owing to their lowest redox potential and lipophilicity whereas rutin and quercitrin-rutinose and rhamnose glycosides-behave vice versa. The ability of the tested glycosides to undergo HAT or SET-type reactions has also been tested using five different analytical assays, including inhibition of cytochrome c-triggered liposome peroxidation. In most cases, rutin proved to be the most unreactive of the four tested glycosides considering either steric or redox reasons whereas the reactivity hierarchy of the other three glycosides were rather assay dependent.
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Affiliation(s)
- Cezara Zagrean-Tuza
- National Institute for Research and Development of Isotopic and Molecular Technology, Cluj-Napoca, Romania. and Faculty of Chemistry and Chemical Engineering, Babes-Bolyai University, Cluj-Napoca, Romania
| | - Augustin C Mot
- Faculty of Chemistry and Chemical Engineering, Babes-Bolyai University, Cluj-Napoca, Romania and National Institute for Research and Development of Isotopic and Molecular Technology, Cluj-Napoca, Romania.
| | - Tomasz Chmiel
- Department of Analytical Chemistry, Faculty of Chemistry, Gdańsk University of Technology, Gdańsk, Poland.
| | - Attila Bende
- National Institute for Research and Development of Isotopic and Molecular Technology, Cluj-Napoca, Romania.
| | - Ioan Turcu
- National Institute for Research and Development of Isotopic and Molecular Technology, Cluj-Napoca, Romania.
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13
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Lux J, Azarkh M, Fitzner L, Keppler JK, Schwarz K, Drescher M, Steffen-Heins A. Amyloid aggregation of spin-labeled β-lactoglobulin. Part II: Identification of spin-labeled protein and peptide sequences after amyloid aggregation. Food Hydrocoll 2021. [DOI: 10.1016/j.foodhyd.2020.106174] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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14
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Biller JR, McPeak JE. EPR Everywhere. APPLIED MAGNETIC RESONANCE 2021; 52:1113-1139. [PMID: 33519097 PMCID: PMC7826499 DOI: 10.1007/s00723-020-01304-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 10/16/2020] [Accepted: 12/06/2020] [Indexed: 06/12/2023]
Abstract
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. The most well-known example of this is the development and recent commercialization of rapid-scan EPR. Both of the Eatons have made it a point to remain knowledgeable on the newest developments in electronics and instrument design. To that end, our review touches on the use of miniaturized electronics and applications of single-board spectrometers based on software-defined radio (SDR) implementations and single-chip voltage-controlled oscillator (VCO) arrays. We also highlight several non-traditional approaches to the EPR experiment such as an EPR spectrometer with a "wand" form factor for analysis of the OxyChip, the EPR-MOUSE which enables non-destructive in situ analysis of many non-conforming samples, and interferometric EPR and frequency swept EPR as alternatives to classical high Q resonant structures.
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Affiliation(s)
| | - Joseph E. McPeak
- University of Denver, Denver, CO 80210 USA
- Berlin Joint EPR Laboratory and EPR4Energy, Department Spins in Energy Conversion and Quantum Information Science (ASPINS), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
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15
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Ismail TM, Mohan N, Sajith PK. Theoretical study of hydrogen bonding interactions in substituted nitroxide radicals. NEW J CHEM 2021. [DOI: 10.1039/d0nj05362g] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Interaction energy (Eint) of hydrogen bonded complexes of nitroxide radicals can be assessed in terms of the deepest minimum of molecular electrostatic potential (Vmin).
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Affiliation(s)
| | - Neetha Mohan
- Department of Chemistry
- Christopher Ingold Building
- University College London (UCL)
- London WC1H 0AJ
- UK
| | - P. K. Sajith
- Department of Chemistry
- Farook College
- Kozhikode
- India
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16
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Alonso L, Mendanha SA, Dorta ML, Alonso A. Analysis of the Interactions of Amphotericin B with the Leishmania Plasma Membrane Using EPR Spectroscopy. J Phys Chem B 2020; 124:10157-10165. [DOI: 10.1021/acs.jpcb.0c07721] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Lais Alonso
- Instituto Federal Goiano, Trindade 76300-000, Goiás, Brazil
- Instituto de Física, Universidade Federal de Goiás, Goiânia 74690-900, Goiás, Brazil
| | | | - Miriam Leandro Dorta
- Instituto de Patologia Tropical e Saúde Publica, Departamento de Imunologia e Patologia Geral, Universidade Federal de Goiás, Goiânia 74690-900, Goiás, Brazil
| | - Antonio Alonso
- Instituto de Física, Universidade Federal de Goiás, Goiânia 74690-900, Goiás, Brazil
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17
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Kuresepi S, Vileno B, Lepoittevin JP, Giménez-Arnau E. Mechanistic Insights on Skin Sensitization to Linalool Hydroperoxides: EPR Evidence on Radical Intermediates Formation in Reconstructed Human Epidermis and 13C NMR Reactivity Studies with Thiol Residues. Chem Res Toxicol 2020; 33:1922-1932. [PMID: 32441093 DOI: 10.1021/acs.chemrestox.0c00125] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Linalool is one of the most commonly used fragrance terpenes in consumer products. While pure linalool is considered as non-allergenic because it has a very low skin sensitization potential, its autoxidation on air leads to allylic hydroperoxides that have been shown to be major skin sensitizers. These hydroperoxides have the potential to form antigens via radical mechanisms. In order to obtain in-depth insights of such reactivity, we first investigated the formation of free radicals derived from linalool hydroperoxides in situ in a model of human reconstructed epidermis by electron paramagnetic resonance combined with spin trapping. The formation of carbon- and oxygen-centered radical species derived from the hydroperoxides was especially evidenced in an epidermis model, mimicking human skin and thus closer to what may happen in vivo. To further investigate these results, we synthesized linalool hydroperoxides containing a 13C-substitution at positions precursor of carbon radicals to elucidate if one of these positions could react with cysteine, its thiol chemical function being one of the most labile groups prone to react through radical mechanisms. Reactions were followed by mono- and bidimensional 13C NMR. We validated that carbon radicals derived from allylic hydrogen abstraction by the initially formed alkoxyl radical and/or from its β-scission can alter directly the lateral chain of cysteine forming adducts via radical processes. Such results provide an original vision on the mechanisms likely involved in the reaction with thiol groups that might be present in the skin environment. Consequently, the present findings are a step ahead toward the understanding of protein binding processes to allergenic allylic hydroperoxides of linalool through the involvement of free radical species and thus of their sensitizing potential.
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Affiliation(s)
- Salen Kuresepi
- Dermatochemistry Laboratory, University of Strasbourg, CNRS, UMR 7177, F-67000 Strasbourg, France
| | - Bertrand Vileno
- POMAM Laboratory, University of Strasbourg, CNRS, UMR 7177, F-67000 Strasbourg, France.,French EPR Federation of Research, REseau NAtional de RPE interDisciplinaire, RENARD, Fédération IR-RPE CNRS 3443, F-67000 Strasbourg, France
| | - Jean-Pierre Lepoittevin
- Dermatochemistry Laboratory, University of Strasbourg, CNRS, UMR 7177, F-67000 Strasbourg, France
| | - Elena Giménez-Arnau
- Dermatochemistry Laboratory, University of Strasbourg, CNRS, UMR 7177, F-67000 Strasbourg, France
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18
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Kovaleva EG, Molochnikov LS, Tambasova D, Marek A, Chestnut M, Osipova VA, Antonov DO, Kirilyuk IA, Smirnov AI. Electrostatic properties of inner nanopore surfaces of anodic aluminum oxide membranes upon high temperature annealing revealed by EPR of pH-sensitive spin probes and labels. J Memb Sci 2020. [DOI: 10.1016/j.memsci.2020.118084] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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19
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Nanocrystals for Improved Drug Delivery of Dexamethasone in Skin Investigated by EPR Spectroscopy. Pharmaceutics 2020; 12:pharmaceutics12050400. [PMID: 32349460 PMCID: PMC7284345 DOI: 10.3390/pharmaceutics12050400] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 04/16/2020] [Accepted: 04/24/2020] [Indexed: 01/29/2023] Open
Abstract
Nanocrystals represent an improvement over the traditional nanocarriers for dermal application, providing the advantages of 100% drug loading, a large surface area, increased adhesion, and the potential for hair follicle targeting. To investigate their advantage for drug delivery, compared to a base cream formulation, dexamethasone (Dx), a synthetic glucocorticoid frequently used for the treatment of inflammatory skin diseases, was covalently linked with the paramagnetic probe 3-(carboxy)-2,2,5,5-tetramethyl-1-pyrrolidinyloxy (PCA) to DxPCA. To investigate the penetration efficiency between these two vehicles, electron paramagnetic resonance (EPR) spectroscopy was used, which allows the quantification of a spin-labeled drug in different skin layers and the monitoring of the drug release. The penetration behavior in excised healthy and barrier-disrupted porcine skin was monitored by EPR, and subsequently analyzed using a numerical diffusion model. As a result, diffusion constants and free energy values in the different layers of the skin were identified for both formulations. Dx-nanocrystals showed a significantly increased drug amount that penetrated into viable epidermis and dermis of intact (factor 3) and barrier-disrupted skin (factor 2.1) compared to the base cream formulation. Furthermore, the observed fast delivery of the spin-labeled drug into the skin (80% DxPCA within 30 min) and a successive release from the aggregate unit into the viable tissue makes these nanocrystals very attractive for clinical applications.
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20
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Bartoš J, Švajdlenková H, Šauša O. Molecular probe dynamics and free volume heterogeneities in n-propanol confined in a regular MCM-41 matrix by ESR and PALS. RSC Adv 2020; 10:2283-2294. [PMID: 35494603 PMCID: PMC9048748 DOI: 10.1039/c9ra09495d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 12/17/2019] [Indexed: 11/21/2022] Open
Abstract
A combined investigation of the spin probe TEMPO mobility and the free volume holes in n-propanol (n-PrOH) confined in a regular virgin MCM-41 matrix by means of ESR or PALS techniques, respectively, is reported. Dynamics of spin probe TEMPO alters at several characteristic ESR temperatures which are close to the characteristic PALS ones reflecting the changes in o-Ps annihilation and the related free volume. Correlations between these characteristic ESR and PALS temperatures indicate the common physical origins of the respective changes in the free volume expansion and the TEMPO mobility in the confined liquid n-PrOH. The significant difference in dynamic heterogeneity of TEMPO after confinement and free volume dispersion reflect the strongly altered structural-dynamic relationships in the confined n-PrOH medium with respect to the bulk situation.
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Affiliation(s)
- Josef Bartoš
- Polymer Institute of SAS Dúbravská Cesta 9 SK-845 41 Bratislava Slovakia
| | | | - Ondrej Šauša
- Institute of Physics of SAS Dúbravská Cesta 9 SK-845 11 Bratislava Slovakia
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21
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Lukešová M, Švajdlenková H, Reuter D, Valić S, Loidl A, Bartoš J. Spin probe interaction and mobility in confined cyclohexane: Effects of pore size and pore surface composition of silica gel matrices. Chem Phys Lett 2019. [DOI: 10.1016/j.cplett.2019.136756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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22
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23
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Dihydroxy-Substituted Coumarins as Fluorescent Probes for Nanomolar-Level Detection of the 4-Amino-TEMPO Spin Label. Int J Mol Sci 2019; 20:ijms20153802. [PMID: 31382639 PMCID: PMC6696051 DOI: 10.3390/ijms20153802] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 07/31/2019] [Accepted: 08/01/2019] [Indexed: 12/18/2022] Open
Abstract
This paper reports on dihydroxycoumarins as fluorescent probes suitable for the detection and determination of the nitroxide radical, namely 4-amino-TEMPO. Since 4-amino-TEMPO is used as a spin label for the detection of various radicals and damage caused by these species, its determination under physiological conditions might help us to understand the mechanism of the oxidative stress. Among different coumarins studied, only dihydroxy-substituted derivatives show high sensitivity, specificity, and selectivity for the nitroxide radical. In this assay, dihydroxy-substituted coumarins under the action of 4-amino-TEMPO show a very fast and significant increase in fluorescence intensity and lifetime. Among them 6,7-dihydroxycoumarin (esculetin) exhibits the strongest fluorescence enhancement (up to 40 times), with an estimated limit of detection equal to 16.7 nM—a significantly lower value when compared with UV-Vis or electron paramagnetic resonance (EPR) spectroscopy. The method is characterized by an easy procedure of sample preparation and very short time of analysis. The mechanism of the interaction between 6,7-dihydroxycoumarin and 4-amino-TEMPO has been examined with the use of a series of complementary techniques, such as steady-state and time-resolved fluorescence spectroscopy, UV-Vis spectroscopy, electron paramagnetic resonance spectroscopy, potentiometric titration, and high-performance liquid chromatography. It has been proven that the only route of the reaction in the system studied is a proton transfer from the molecule of esculetin to the amino group of the nitroxide. Biological studies performed on prostate cancer cells, breast cancer cells, and normal skin fibroblasts revealed significant anticancer properties of 6,7-dihydroxycoumarin, which caused a considerable decrease in the viability and number of cancer cells, and affected their morphology, contrary to normal fibroblasts. Furthermore, the experiment performed on prostate cancer cells showed that fluorescence emission of esculetin is closely related to intracellular pH—the higher pH, the higher observed fluorescence intensity (in accordance with a chemical experiment). On the other hand, the studies performed in different pH levels revealed that when pH of the solution increases, the observed fluorescence intensity enhancement under the action of 4-amino-TEMPO decreases (better sensing properties of esculetin towards the nitroxide in lower pH).
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24
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Haeri HH, Schunk B, Tomaszewski J, Schimm H, Gelos MJ, Hinderberger D. Fatty Acid Binding to Human Serum Albumin in Blood Serum Characterized by EPR Spectroscopy. ChemistryOpen 2019; 8:650-656. [PMID: 31143562 PMCID: PMC6532450 DOI: 10.1002/open.201900113] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 04/29/2019] [Indexed: 12/31/2022] Open
Abstract
One of the functions of Human Serum Albumin (HSA) is binding and transport of fatty acids. This ability could be altered by the presence of several blood components such as toxins or peptides - which in turn alters the functionality of the protein. We aim at characterizing HSA and its fatty acid binding in native serum environment. Native ligand binding and deviations from normal function can be monitored by electron paramagnetic resonance (EPR) spectroscopy using spin labeled fatty acids (FAs). Blood serum from healthy individuals is used to examine healthy HSA in its natural physiological conditions at different loading ratios of protein to FAs. Among the EPR spectroscopic parameters (like hyperfine coupling, line shape, rotational correlation time and population of different binding sites) the rotational correlation time is found to differ significantly between binding sites of the protein, especially at loading ratios of four FAs per HSA. Although differences are observed between individual samples, a general trend regarding the dynamics of healthy HSA at different loading ratios could be obtained and compared to a reference of purified commercially available HSA in buffer.
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Affiliation(s)
- Haleh H. Haeri
- Institut für ChemieMartin-Luther-Universität Halle-WittenbergVon-Danckelmann-Platz 406120Halle (Saale)Germany
| | - Bettina Schunk
- Department of General and Visceral SurgeryAlfried Krupp Krankenhaus EssenHellweg 10045276EssenGermany
| | - Jörg Tomaszewski
- Department of General and Visceral SurgeryAlfried Krupp Krankenhaus EssenHellweg 10045276EssenGermany
| | - Heike Schimm
- Institut für ChemieMartin-Luther-Universität Halle-WittenbergVon-Danckelmann-Platz 406120Halle (Saale)Germany
| | - Marcos J. Gelos
- Department of General and Visceral SurgeryAlfried Krupp Krankenhaus EssenHellweg 10045276EssenGermany
- Faculty of Health sciencesUniversity of Witten / HerdeckeAlfred-Herrhausen-Straße 5058455WittenGermany
| | - Dariush Hinderberger
- Institut für ChemieMartin-Luther-Universität Halle-WittenbergVon-Danckelmann-Platz 406120Halle (Saale)Germany
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25
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Glasbrenner M, Vogler S, Ochsenfeld C. Linear and sublinear scaling computation of the electronic g-tensor at the density functional theory level. J Chem Phys 2019; 150:024104. [DOI: 10.1063/1.5066266] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Michael Glasbrenner
- Chair of Theoretical Chemistry and Center for Integrated Protein Science Munich (CIPSM), Department of Chemistry, University of Munich (LMU), Butenandtstr. 7, 81377 Munich, Germany
| | - Sigurd Vogler
- Chair of Theoretical Chemistry and Center for Integrated Protein Science Munich (CIPSM), Department of Chemistry, University of Munich (LMU), Butenandtstr. 7, 81377 Munich, Germany
| | - Christian Ochsenfeld
- Chair of Theoretical Chemistry and Center for Integrated Protein Science Munich (CIPSM), Department of Chemistry, University of Munich (LMU), Butenandtstr. 7, 81377 Munich, Germany
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26
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Nikolantonaki M, Coelho C, Noret L, Zerbib M, Vileno B, Champion D, Gougeon RD. Measurement of white wines resistance against oxidation by Electron Paramagnetic Resonance spectroscopy. Food Chem 2019; 270:156-161. [DOI: 10.1016/j.foodchem.2018.07.052] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 07/04/2018] [Accepted: 07/08/2018] [Indexed: 10/28/2022]
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Soetbeer J, Gast P, Walish JJ, Zhao Y, George C, Yang C, Swager TM, Griffin RG, Mathies G. Conformation of bis-nitroxide polarizing agents by multi-frequency EPR spectroscopy. Phys Chem Chem Phys 2018; 20:25506-25517. [PMID: 30277229 PMCID: PMC7256712 DOI: 10.1039/c8cp05236k] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The chemical structure of polarizing agents critically determines the efficiency of dynamic nuclear polarization (DNP). For cross-effect DNP, biradicals are the polarizing agents of choice and the interaction and relative orientation of the two unpaired electrons should be optimal. Both parameters are affected by the molecular structure of the biradical in the frozen glassy matrix that is typically used for DNP/MAS NMR and likely differs from the structure observed with X-ray crystallography. We have determined the conformations of six bis-nitroxide polarizing agents, including the highly efficient AMUPol, in their DNP matrix with EPR spectroscopy at 9.7 GHz, 140 GHz, and 275 GHz. The multi-frequency approach in combination with an advanced fitting routine allows us to reliably extract the interaction and relative orientation of the nitroxide moieties. We compare the structures of six bis-nitroxides to their DNP performance at 500 MHz/330 GHz.
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Affiliation(s)
- Janne Soetbeer
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Peter Gast
- Department of Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, PO Box 9504, 2300 RA Leiden, The Netherlands
| | - Joseph J Walish
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yanchuan Zhao
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Christy George
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Chen Yang
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Timothy M Swager
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Robert G Griffin
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Guinevere Mathies
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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28
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Švajdlenková H, Arrese-Igor S, Nógellová Z, Alegría A, Bartoš J. Molecular dynamic heterogeneity in relation to free volume and relaxation dynamics in organic glass-formers: oligomeric cis-1,4-poly(isoprene). Phys Chem Chem Phys 2018; 19:15215-15226. [PMID: 28561833 DOI: 10.1039/c7cp00446j] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Herein, a combined study of the molecular rotation dynamics and free volume in cis-1,4-poly(isoprene) using two external probing techniques via ESR and PALS together with relaxation dynamics of the host medium via BDS is presented. The spectral evolution of the spin probe TEMPO from simulations over a wide range from 100 K up to 300 K exhibits three different regions of its correlation time consisting of a slow regime at low temperatures followed by the molecular dynamic heterogeneity zone from T = T = 155 K = 0.82 × T up to Tc ≅ 236 K = 1.26 × T and ending with a fast regime at high temperatures with the further characteristic ESR temperatures, T = 186 K ≅ T and T = 260 K. These are in close coincidence with four characteristic PALS temperatures: T = 160 K, T = 190 K, T = 227 K, and T = 263 K. Finally, using BDS, we revealed that the high-frequency features of the structural relaxation of 1,4-PIP 0.8k were related to the observed effects in the ESR and PALS response of the liquid state.
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Affiliation(s)
- H Švajdlenková
- Department of Structure and Physical Properties, Polymer Institute of SAS, Dúbravská cesta 9, SK-845 41 Bratislava, Slovakia.
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Sahu ID, Craig AF, Dunagum MM, McCarrick RM, Lorigan GA. Characterization of Bifunctional Spin Labels for Investigating the Structural and Dynamic Properties of Membrane Proteins Using EPR Spectroscopy. J Phys Chem B 2017; 121:9185-9195. [PMID: 28877443 DOI: 10.1021/acs.jpcb.7b07631] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Site-directed spin labeling (SDSL) coupled with electron paramagnetic resonance (EPR) spectroscopy is a very powerful technique to study structural and dynamic properties of membrane proteins. The most widely used spin label is methanthiosulfonate (MTSL). However, the flexibility of this spin label introduces greater uncertainties in EPR measurements obtained for determining structures, side-chain dynamics, and backbone motion of membrane protein systems. Recently, a newer bifunctional spin label (BSL), 3,4-bis(methanethiosulfonylmethyl)-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-1-yloxy, has been introduced to overcome the dynamic limitations associated with the MTSL spin label and has been invaluable in determining protein backbone dynamics and inter-residue distances due to its restricted internal motion and fewer size restrictions. While BSL has been successful in providing more accurate information about the structure and dynamics of several proteins, a detailed characterization of the spin label is still lacking. In this study, we characterized BSLs by performing CW-EPR spectral line shape analysis as a function of temperature on spin-labeled sites inside and outside of the membrane for the integral membrane protein KCNE1 in POPC/POPG lipid bilayers and POPC/POPG lipodisq nanoparticles. The experimental data revealed a powder pattern spectral line shape for all of the KCNE1-BSL samples at 296 K, suggesting the motion of BSLs approaches the rigid limit regime for these series of samples. BSLs were further utilized to report for the first time the distance measurement between two BSLs attached on an integral membrane protein KCNE1 in POPC/POPG lipid bilayers at room temperature using dipolar line broadening CW-EPR spectroscopy. The CW dipolar line broadening EPR data revealed a 15 ± 2 Å distance between doubly attached BSLs on KCNE1 (53/57-63/67) which is consistent with molecular dynamics modeling and the solution NMR structure of KCNE1 which yielded a distance of 17 Å. This study demonstrates the utility of investigating the structural and dynamic properties of membrane proteins in physiologically relevant membrane mimetics using BSLs.
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Affiliation(s)
- Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Andrew F Craig
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Megan M Dunagum
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Robert M McCarrick
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
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30
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Localization of dexamethasone within dendritic core-multishell (CMS) nanoparticles and skin penetration properties studied by multi-frequency electron paramagnetic resonance (EPR) spectroscopy. Eur J Pharm Biopharm 2017; 116:94-101. [DOI: 10.1016/j.ejpb.2016.10.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 09/30/2016] [Accepted: 10/12/2016] [Indexed: 12/27/2022]
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31
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Eckert H. Advanced Magnetic Resonance Techniques for the Structural Characterization of Aminoxyl Radicals and Their Inorganic-Organic Nanocomposite Systems. Chemistry 2017; 23:5893-5914. [PMID: 27862449 DOI: 10.1002/chem.201604685] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Indexed: 11/10/2022]
Abstract
Electron and nuclear spins are extremely sensitive probes of their local structural and dynamic surroundings. Their Zeeman energy levels are modified by different types of local magnetic and electric fields created by their structural environment, which influence their magnetic resonance condition. For this reason, electron spin resonance (ESR) and nuclear magnetic resonance (NMR) spectroscopies have become extremely powerful tools of structural analysis, which are being widely used for the structural characterization of complex solids. Following a brief introduction into the basic theoretical foundations the most commonly used techniques and their application towards the structural characterization of paramagnetic solids based on aminoxyl radicals and their inorganic-organic nanocomposites will be described. Both ESR and NMR observables are useful for monitoring intermolecular interactions between unpaired electron spins, which are particularly important for the design of organically based ferromagnetic systems. ESR and NMR methods based on this effect can be used for monitoring the synthesis of polynitroxides and for evaluating the catalytic function of aminoxyl intercalation compounds. Finally, the sensitivity of ESR signals to motional dynamics can be exploited for characterizing molecule-surface interactions in nanocomposite systems. In the context of the latter work recently developed signal enhancement strategies are described, using polarization transfer from electron spins to nuclear spins for NMR spectroscopic detection.
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Affiliation(s)
- Hellmut Eckert
- Institut für Physikalische Chemie, WWU Münster, Corrensstraße 30, 48149, Münster, Germany.,Instituto de Física São Carlos, Universidade de São Paulo, CP 369, 13560-970, São Carlos, S.P., Brasil
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32
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Gast P, Mance D, Zurlo E, Ivanov KL, Baldus M, Huber M. A tailored multi-frequency EPR approach to accurately determine the magnetic resonance parameters of dynamic nuclear polarization agents: application to AMUPol. Phys Chem Chem Phys 2017; 19:3777-3781. [DOI: 10.1039/c6cp05864g] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Multi- and very high-field electron paramagnetic resonance provides essential parameters to characterize dynamic nuclear polarization agents.
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Affiliation(s)
- P. Gast
- Department of Physics
- Huygens-Kamerlingh Onnes Laboratory
- Leiden University
- 2300 RA Leiden
- The Netherlands
| | - D. Mance
- NMR Spectroscopy
- Bijvoet Center for Biomolecular Research
- Utrecht University
- Utrecht
- The Netherlands
| | - E. Zurlo
- Department of Physics
- Huygens-Kamerlingh Onnes Laboratory
- Leiden University
- 2300 RA Leiden
- The Netherlands
| | - K. L. Ivanov
- International Tomography Center
- Siberian Branch of the Russian Academy of Science
- Novosibirsk 630090
- Russia
- Novosibirsk State University
| | - M. Baldus
- NMR Spectroscopy
- Bijvoet Center for Biomolecular Research
- Utrecht University
- Utrecht
- The Netherlands
| | - M. Huber
- Department of Physics
- Huygens-Kamerlingh Onnes Laboratory
- Leiden University
- 2300 RA Leiden
- The Netherlands
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33
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Drug distribution in nanostructured lipid particles. Eur J Pharm Biopharm 2017; 110:19-23. [DOI: 10.1016/j.ejpb.2016.10.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 09/16/2016] [Accepted: 10/22/2016] [Indexed: 11/21/2022]
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34
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Lohmiller T, Vibhute MA, Lubitz W, Savitsky A. Multifrequency Multiresonance EPR Investigation of Halogen-bonded Complexes Involving Neutral Nitroxide Radicals. ACTA ACUST UNITED AC 2016. [DOI: 10.1515/zpch-2016-0870] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Halogen-bonded complexes with neutral nitroxide radicals as the Lewis base have been investigated in liquid and frozen solutions by multifrequency CW and pulse EPR spectroscopies, including ENDOR and ELDOR-detected NMR (EDNMR) techniques. The non-covalent interaction with iodopentafluorobenzene as halogen-bond donor is shown to affect a variety of EPR parameters of the stable nitroxide radicals. In liquid solution, only bulk effects on the EPR signal, i.e. isotropic g value, isotropic 14N hyperfine coupling and linewidth, are observed. Experiments on frozen solutions allow for a more in-depth dissection of complexing effects. W-band EPR spectra at cryogenic temperatures exhibit multiple signal components of different 14N hyperfine interactions and spectral widths. This demonstrates the coexistence of several halogen-bonded complexes that differ in donor-acceptor binding geometries. These complexes have different relaxation properties, which allow for their spectral discrimination. 19F ENDOR experiments prove the origin of these effects to be different specific intermolecular interactions rather than a consequence of changes in the solvation environment. The EPR spectra yet reveal a strong influence of solvent composition on the amount of the various complexes formed. The introduced methodology for the characterization of such adducts improves our understanding of halogen bonding and could be helpful in the development of tailor-made donors and complexes for specific applications.
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Affiliation(s)
- Thomas Lohmiller
- Max-Planck-Institut für Chemische Energiekonversion, 45470 Mülheim an der Ruhr, Germany
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Mahesh A. Vibhute
- Lehrstuhl für Physikalische Chemie II, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Wolfgang Lubitz
- Max-Planck-Institut für Chemische Energiekonversion, 45470 Mülheim an der Ruhr, Germany
| | - Anton Savitsky
- Max-Planck-Institut für Chemische Energiekonversion, 45470 Mülheim an der Ruhr, Germany
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35
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Mardis KL, Webb JN, Holloway T, Niklas J, Poluektov OG. Electronic Structure of Fullerene Acceptors in Organic Bulk-Heterojunctions: A Combined EPR and DFT Study. J Phys Chem Lett 2015; 6:4730-5. [PMID: 26569578 PMCID: PMC4985179 DOI: 10.1021/acs.jpclett.5b02111] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Organic photovoltaic (OPV) devices are a promising alternative energy source. Attempts to improve their performance have focused on the optimization of electron-donating polymers, while electron-accepting fullerenes have received less attention. Here, we report an electronic structure study of the widely used soluble fullerene derivatives PC61BM and PC71BM in their singly reduced state, that are generated in the polymer:fullerene blends upon light-induced charge separation. Density functional theory (DFT) calculations characterize the electronic structures of the fullerene radical anions through spin density distributions and magnetic resonance parameters. The good agreement of the calculated magnetic resonance parameters with those determined experimentally by advanced electron paramagnetic resonance (EPR) allows the validation of the DFT calculations. Thus, for the first time, the complete set of magnetic resonance parameters including directions of the principal g-tensor axes were determined. For both molecules, no spin density is present on the PCBM side chain, and the axis of the largest g-value lies along the PCBM molecular axis. While the spin density distribution is largely uniform for PC61BM, it is not evenly distributed for PC71BM.
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Affiliation(s)
- Kristy L Mardis
- Department of Chemistry and Physics, Chicago State University , Chicago, Illinois 60628, United States
| | - Jeremy N Webb
- Department of Chemistry and Physics, Chicago State University , Chicago, Illinois 60628, United States
| | - Tarita Holloway
- Department of Chemistry and Physics, Chicago State University , Chicago, Illinois 60628, United States
| | - Jens Niklas
- Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Oleg G Poluektov
- Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
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36
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Witwicki M, Jezierska J. Toward an Understanding of the Ambiguous Electron Paramagnetic Resonance Spectra of the Iminoxy Radical from o-Fluorobenzaldehyde Oxime: Density Functional Theory and ab Initio Studies. J Phys Chem A 2015; 119:9109-20. [PMID: 26258434 DOI: 10.1021/acs.jpca.5b06143] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Iminoxy radicals (R1R2C═N—O•) possess an inherent ability to exist as E and Z isomers. Although isotropic hyperfine couplings for the species with R1 = H allow one to distinguish between E and Z, unequivocal assignment of the parameters observed in the EPR spectra of the radicals without the hydrogen atom at the azomethine carbon to the right isomer is not a simple task. The iminoxyl derived from o-fluoroacetophenone oxime (R1 = CH3 and R2 = o-FC6H5) appears to be a case in point. Moreover, for its two isomers the rotation of the o-FC6H5 group brings into existence the syn and anti conformers, depending on the mutual orientation of the F atom and C═N—O• group, making a description of hyperfine couplings to structure even more challenging. To accomplish this, a vast array of theoretical methods (DFT, OO-SCS-MP2, QCISD) was used to calculate the isotropic hyperfine couplings. The comparison between experimental and theoretical values revealed that the E isomer is the dominant radical form, for which a fast interconversion between anti and syn conformers is expected. In addition, the origin of the significant AF increase with solvent polarity was analyzed.
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37
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Witwicki M. Theoretical Characterisation of Phosphinyl Radicals and Their Magnetic Properties: g Matrix. Chemphyschem 2015; 16:1912-25. [PMID: 25873130 DOI: 10.1002/cphc.201500121] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Indexed: 11/11/2022]
Abstract
The g matrices (g tensors) of various phosphinyl radicals (R2 P(.) ) were calculated using the DFT and multireference configuration interaction (MRCI) methods. The g matrices were distinctly dependent on the molecular structure of the radical. To thoroughly examine this dependence, the contributions from individual atoms and excited states were calculated. The former revealed the gain from the phosphorus atom to be preeminent unless PO or PS bonds are present in the radical molecule. The contributions owing to excited states arising from electronic transitions between doubly occupied molecular orbitals and the SOMO were clearly positive, as in the case of semiquinone and niroxide radicals. The transitions from the phosphorus lone pair were of paramount importance. Surprisingly, unlike for semiquinones and nitroxides, a significant negative contribution was observed from excitations from the SOMO to unoccupied molecular orbitals. For radicals with PO bonds, this contribution to the g2 component was dominant.
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Affiliation(s)
- Maciej Witwicki
- Faculty of Chemistry, Wroclaw University, 14 F. Joliot-Curie St., Wroclaw 50-283 (Poland).
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38
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Merunka D, Peric M, Peric M. Study of nanostructural organization of ionic liquids by electron paramagnetic resonance spectroscopy. J Phys Chem B 2015; 119:3185-93. [PMID: 25594422 PMCID: PMC4871252 DOI: 10.1021/jp512487y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The X-band electron paramagnetic resonance spectroscopy (EPR) of a stable, spherical nitroxide spin probe, perdeuterated 2,2,6,6-tetramethyl-4-oxopiperidine-1-oxyl (pDTO) has been used to study the nanostructural organization of a series of 1-alkyl-3-methylimidazolium tetrafluoroborate ionic liquids (ILs) with alkyl chain lengths from two to eight carbons. By employing nonlinear least-squares fitting of the EPR spectra, we have obtained values of the rotational correlation time and hyperfine coupling splitting of pDTO to high precision. The rotational correlation time of pDTO in ILs and squalane, a viscous alkane, can be fit very well to a power law functionality with a singular temperature, which often describes a number of physical quantities measured in supercooled liquids. The viscosity of the ILs and squalane, taken from the literature, can also be fit to the same power law expression, which means that the rotational correlation times and the ionic liquid viscosities have similar functional dependence on temperature. The apparent activation energy of both the rotational correlation time of pDTO and the viscous flow of ILs and squalane increases with decreasing temperature; in other words, they exhibit strong non-Arrhenius behavior. The rotational correlation time of pDTO as a function of η/T, where η is the shear viscosity and T is the temperature, is well described by the Stokes-Einstein-Debye (SED) law, while the hydrodynamic probe radii are solvent dependent and are smaller than the geometric radius of the probe. The temperature dependence of hyperfine coupling splitting is the same in all four ionic liquids. The value of the hyperfine coupling splitting starts decreasing with increasing alkyl chain length in the ionic liquids in which the number of carbons in the alkyl chain is greater than four. This decrease together with the decrease in the hydrodynamic radius of the probe indicates a possible existence of nonpolar nanodomains.
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Affiliation(s)
| | - Mirna Peric
- Department of Physics and Astronomy and The Center for Supramolecular Studies California State University at Northridge, Northridge, CA 91330
| | - Miroslav Peric
- Department of Physics and Astronomy and The Center for Supramolecular Studies California State University at Northridge, Northridge, CA 91330
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39
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Gozdziewska M, Cichowicz G, Markowska K, Zawada K, Megiel E. Nitroxide-coated silver nanoparticles: synthesis, surface physicochemistry and antibacterial activity. RSC Adv 2015. [DOI: 10.1039/c5ra09366j] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We report the synthesis of well-defined silver nanoparticles with high antibacterial activity. Nitroxides on their surface may be oxidized under the influence of ROS to oxoammonium ions which are capable of interacting with bacterial membrane.
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Affiliation(s)
| | | | - Katarzyna Markowska
- University of Warsaw
- Faculty of Biology
- Institute of Microbiology
- Department of Bacterial Genetics
- 02-096 Warsaw
| | - Katarzyna Zawada
- Medical University of Warsaw
- Faculty of Pharmacy with the Laboratory Medicine Division
- 07-097 Warsaw
- Poland
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40
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Peric I, Merunka D, Bales BL, Peric M. Hydrodynamic and nonhydrodynamic contributions to the bimolecular collision rates of solute molecules in supercooled bulk water. J Phys Chem B 2014; 118:7128-35. [PMID: 24874024 PMCID: PMC4076007 DOI: 10.1021/jp501330x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Bimolecular collision rate constants of a model solute are measured in water at T = 259-303 K, a range encompassing both normal and supercooled water. A stable, spherical nitroxide spin probe, perdeuterated 2,2,6,6-tetramethyl-4-oxopiperidine-1-oxyl, is studied using electron paramagnetic resonance spectroscopy (EPR), taking advantage of the fact that the rotational correlation time, τ(R), the mean time between successive spin exchanges within a cage, τ(RE), and the long-time-averaged spin exchange rate constants, K(ex), of the same solute molecule may be measured independently. Thus, long- and short-time translational diffusion behavior may be inferred from K(ex) and τ(RE), respectively. In order to measure K(ex), the effects of dipole-dipole interactions (DD) on the EPR spectra must be separated, yielding as a bonus the DD broadening rate constants that are related to the dephasing rate constant due to DD, W(dd). We find that both K(ex) and W(dd) behave hydrodynamically; that is to say they vary monotonically with T/η or η/T, respectively, where η is the shear viscosity, as predicted by the Stokes-Einstein equation. The same is true of the self-diffusion of water. In contrast, τ(RE) does not follow hydrodynamic behavior, varying rather as a linear function of the density reaching a maximum at 276 ± 2 K near where water displays a maximum density.
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Affiliation(s)
- Ida Peric
- Department of Physics and Astronomy and The Center for Supramolecular Studies, California State University at Northridge , Northridge, California 91330, United States
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41
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Nalepa A, Möbius K, Lubitz W, Savitsky A. High-field ELDOR-detected NMR study of a nitroxide radical in disordered solids: towards characterization of heterogeneity of microenvironments in spin-labeled systems. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 242:203-213. [PMID: 24685717 DOI: 10.1016/j.jmr.2014.02.026] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 02/27/2014] [Accepted: 02/28/2014] [Indexed: 06/03/2023]
Abstract
The combination of high-field EPR with site-directed spin-labeling (SDSL) techniques employing nitroxide radicals has turned out to be particularly powerful in probing the polarity and proticity characteristics of protein/matrix systems. This information is concluded from the principal components of the nitroxide Zeeman (g), nitrogen hyperfine (A) and quadrupole (P) tensors of the spin labels attached to specific sites. Recent multi-frequency high-field EPR studies underlined the complexity of the problem to treat the nitroxide microenvironment in proteins adequately due to inherent heterogeneities which result in several principal x-components of the nitroxide g-tensor. Concomitant, but distinctly different nitrogen hyperfine components could, however, not be determined from high-field cw EPR experiments owing to the large intrinsic EPR linewidth in fully protonated guest/host systems. It is shown in this work that, using the W-band (95GHz) ELDOR- (electron-electron double resonance) detected NMR (EDNMR) method, different principal nitrogen hyperfine, Azz, and quadrupole, Pzz, tensor values of a nitroxide radical in glassy 2-propanol matrix can be measured with high accuracy. They belong to nitroxides with different hydrogen-bond situations. The satisfactory resolution and superior sensitivity of EDNMR as compared to the standard ENDOR (electron-nuclear double resonance) method are demonstrated.
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Affiliation(s)
- Anna Nalepa
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Klaus Möbius
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, D-45470 Mülheim an der Ruhr, Germany; Department of Physics, Free University Berlin, Arnimallee 14, D-14195 Berlin, Germany
| | - Wolfgang Lubitz
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Anton Savitsky
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, D-45470 Mülheim an der Ruhr, Germany.
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42
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43
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Gast P, Herbonnet RTL, Klare J, Nalepa A, Rickert C, Stellinga D, Urban L, Möbius K, Savitsky A, Steinhoff HJ, Groenen EJJ. Hydrogen bonding of nitroxide spin labels in membrane proteins. Phys Chem Chem Phys 2014; 16:15910-6. [DOI: 10.1039/c4cp01741b] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
On the basis of experiments at 275 GHz, we reconsider the dependence of the continuous-wave EPR spectra of nitroxide spin-labeled protein sites in sensory- and bacteriorhodopsin on the micro-environment.
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Affiliation(s)
- P. Gast
- Huygens-Kamerlingh Onnes Laboratory
- Department of Physics
- Leiden University
- NL-2300 RA Leiden, The Netherlands
| | - R. T. L. Herbonnet
- Huygens-Kamerlingh Onnes Laboratory
- Department of Physics
- Leiden University
- NL-2300 RA Leiden, The Netherlands
| | - J. Klare
- Department of Physics
- University of Osnabrück
- D-49076 Osnabrück, Germany
| | - A. Nalepa
- Max Planck Institute for Chemical Energy Conversion
- D-45470 Mülheim an der Ruhr, Germany
| | - C. Rickert
- Department of Physics
- University of Osnabrück
- D-49076 Osnabrück, Germany
| | - D. Stellinga
- Huygens-Kamerlingh Onnes Laboratory
- Department of Physics
- Leiden University
- NL-2300 RA Leiden, The Netherlands
| | - L. Urban
- Department of Physics
- University of Osnabrück
- D-49076 Osnabrück, Germany
| | - K. Möbius
- Max Planck Institute for Chemical Energy Conversion
- D-45470 Mülheim an der Ruhr, Germany
- Department of Physics
- Free University Berlin
- D-14195 Berlin, Germany
| | - A. Savitsky
- Max Planck Institute for Chemical Energy Conversion
- D-45470 Mülheim an der Ruhr, Germany
| | - H.-J. Steinhoff
- Department of Physics
- University of Osnabrück
- D-49076 Osnabrück, Germany
| | - E. J. J. Groenen
- Huygens-Kamerlingh Onnes Laboratory
- Department of Physics
- Leiden University
- NL-2300 RA Leiden, The Netherlands
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44
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Zawada K, Tomaszewski W, Megiel E. A smart synthesis of gold/polystyrene core–shell nanohybrids using TEMPO coated nanoparticles. RSC Adv 2014. [DOI: 10.1039/c4ra01770f] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We propose a novel route for preparation of core–shell nanostructures based on the macroradicals coupling with nitroxides attached to the nanoparticle surface.
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Affiliation(s)
- Katarzyna Zawada
- Medical University of Warsaw
- Faculty of Pharmacy with the Laboratory Medicine Division
- Warsaw, Poland
| | | | - Elżbieta Megiel
- University of Warsaw
- Faculty of Chemistry
- 02-093 Warsaw, Poland
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45
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Krumkacheva OA, Fedin MV, Polovyanenko DN, Jicsinszky L, Marque SRA, Bagryanskaya EG. Structural Equilibrium in New Nitroxide-Capped Cyclodextrins: CW and Pulse EPR Study. J Phys Chem B 2013; 117:8223-31. [DOI: 10.1021/jp404173j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Olesya A. Krumkacheva
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090,
Russia
- Novosibirsk State University, Pirogova strasse 2, Novosibirsk 630090,
Russia
| | - Matvey V. Fedin
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090,
Russia
| | - Dmitry N. Polovyanenko
- N. N.Voroztsov Novosibirsk Institute of Organic Chemistry SB RAS, Pr. Lavrentjeva
9, Novosibirsk 630090, Russia
| | | | - Sylvain R. A. Marque
- Aix-Marseille Université, CNRS-ICR UMR 7273, case 521, Avenue
Escadrille Normandie-Niemen,
13397 Marseille cedex 20, France
| | - Elena G. Bagryanskaya
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090,
Russia
- N. N.Voroztsov Novosibirsk Institute of Organic Chemistry SB RAS, Pr. Lavrentjeva
9, Novosibirsk 630090, Russia
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46
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47
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Behrends F, Wagner H, Studer A, Niehaus O, Pöttgen R, Eckert H. Polynitroxides from Alkoxyamine Monomers: Structural and Kinetic Investigations by Solid State NMR. Macromolecules 2013. [DOI: 10.1021/ma400351q] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Frederik Behrends
- Institute of Physical
Chemistry, WWU Münster, Corrensstraße
30, 48149 Münster,
Germany
| | - Hendrik Wagner
- Organic Chemistry Institute, WWU Münster, Corrensstraße 40, 48149 Münster,
Germany
| | - Armido Studer
- Organic Chemistry Institute, WWU Münster, Corrensstraße 40, 48149 Münster,
Germany
| | - Oliver Niehaus
- Institute of Inorganic
and Analytical
Chemistry, WWU Münster, Corrensstraße
30, 48149 Münster, Germany
| | - Rainer Pöttgen
- Institute of Inorganic
and Analytical
Chemistry, WWU Münster, Corrensstraße
30, 48149 Münster, Germany
| | - Hellmut Eckert
- Institute of Physical
Chemistry, WWU Münster, Corrensstraße
30, 48149 Münster,
Germany
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48
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Peric I, Merunka D, Bales BL, Peric M. Rotation of Four Small Nitroxide Probes in Supercooled Bulk Water. J Phys Chem Lett 2013; 4:508-513. [PMID: 23493516 PMCID: PMC3593304 DOI: 10.1021/jz302107x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Using a precise method of least-squares nonlinear electron paramagnetic resonance (EPR) line fitting, we have obtained experimental evidence of a decoupling of the rotational motion of four nitroxide spin probes from the viscosity of bulk water at 277 K. This decoupling is about 50 K higher than another such phenomenon observed in interstitial supercooled water of polycrystalline ice by Banerjee et al. (Proc Natl Acad Sci USA 106 (2009) 11448-11453). Above 277 K the activation energies of the rotation of the probes and water viscosity are very close, while in the supercooled region the activation energies of the probes' rotation are greater than that of the viscosity of water. The rotational correlation times of the probes can be fit well to a power law functionality with a singular temperature. The temperature dependence of the hydrodynamic radii of the probes indicates two distinct dynamical regions, which cross at 277 K.
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Affiliation(s)
- Ida Peric
- Department of Physics and Astronomy and The Center for Supramolecular Studies, California State University at Northridge, Northridge, CA 91330
| | - Dalibor Merunka
- Department of Physics and Astronomy and The Center for Supramolecular Studies, California State University at Northridge, Northridge, CA 91330
| | - Barney L. Bales
- Department of Physics and Astronomy and The Center for Supramolecular Studies, California State University at Northridge, Northridge, CA 91330
| | - Miroslav Peric
- Department of Physics and Astronomy and The Center for Supramolecular Studies, California State University at Northridge, Northridge, CA 91330
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Voinov MA, Rivera-Rivera I, Smirnov AI. Surface electrostatics of lipid bilayers by EPR of a pH-sensitive spin-labeled lipid. Biophys J 2013; 104:106-16. [PMID: 23332063 DOI: 10.1016/j.bpj.2012.11.3806] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2012] [Revised: 10/02/2012] [Accepted: 11/13/2012] [Indexed: 01/21/2023] Open
Abstract
Many biophysical processes such as insertion of proteins into membranes and membrane fusion are governed by bilayer electrostatic potential. At the time of this writing, the arsenal of biophysical methods for such measurements is limited to a few techniques. Here we describe a, to our knowledge, new spin-probe electron paramagnetic resonance (EPR) approach for assessing the electrostatic surface potential of lipid bilayers that is based on a recently synthesized EPR probe (IMTSL-PTE) containing a reversibly ionizable nitroxide tag attached to the lipids' polar headgroup. EPR spectra of the probe directly report on its ionization state and, therefore, on electrostatic potential through changes in nitroxide magnetic parameters and the degree of rotational averaging. Further, the lipid nature of the probe provides its full integration into lipid bilayers. Tethering the nitroxide moiety directly to the lipid polar headgroup defines the location of the measured potential with respect to the lipid bilayer interface. Electrostatic surface potentials measured by EPR of IMTSL-PTE show a remarkable (within ±2%) agreement with the Gouy-Chapman theory for anionic DMPG bilayers in fluid (48°C) phase at low electrolyte concentration (50 mM) and in gel (17°C) phase at 150-mM electrolyte concentration. This agreement begins to diminish for DMPG vesicles in gel phase (17°C) upon varying electrolyte concentration and fluid phase bilayers formed from DMPG/DMPC and POPG/POPC mixtures. Possible reasons for such deviations, as well as the proper choice of an electrostatically neutral reference interface, have been discussed. Described EPR method is expected to be fully applicable to more-complex models of cellular membranes.
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Affiliation(s)
- Maxim A Voinov
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina, USA
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Eaton SS, Eaton GR. The world as viewed by and with unpaired electrons. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 223:151-63. [PMID: 22975244 PMCID: PMC3496796 DOI: 10.1016/j.jmr.2012.07.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Revised: 07/26/2012] [Accepted: 07/27/2012] [Indexed: 06/01/2023]
Abstract
Recent advances in electron paramagnetic resonance (EPR) include capabilities for applications to areas as diverse as archeology, beer shelf life, biological structure, dosimetry, in vivo imaging, molecular magnets, and quantum computing. Enabling technologies include multifrequency continuous wave, pulsed, and rapid scan EPR. Interpretation is enhanced by increasingly powerful computational models.
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Affiliation(s)
- Sandra S Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA
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