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Michaelis VK, Corzilius B, Smith AA, Griffin RG. Dynamic nuclear polarization of 17O: direct polarization. J Phys Chem B 2013; 117:14894-906. [PMID: 24195759 PMCID: PMC3922122 DOI: 10.1021/jp408440z] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Dynamic nuclear polarization of (17)O was studied using four different polarizing agents: the biradical TOTAPOL and the monoradicals trityl and SA-BDPA, as well as a mixture of the latter two. Field profiles, DNP mechanisms, and enhancements were measured to better understand and optimize directly polarizing this low-gamma quadrupolar nucleus using both mono- and biradical polarizing agents. Enhancements were recorded at <88 K and were >100 using the trityl (OX063) radical and <10 with the other polarizing agents. The >10,000-fold savings in acquisition time enabled a series of biologically relevant small molecules to be studied with small sample sizes and the measurement of various quadrupolar parameters. The results are discussed with comparison to room temperature studies and GIPAW quantum chemical calculations. These experimental results illustrate the strength of high field DNP and the importance of radical selection for studying low-gamma nuclei.
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Affiliation(s)
- Vladimir K. Michaelis
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | | | | | - Robert G. Griffin
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
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52
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Gajan D, Schwarzwälder M, Conley MP, Grüning WR, Rossini AJ, Zagdoun A, Lelli M, Yulikov M, Jeschke G, Sauvée C, Ouari O, Tordo P, Veyre L, Lesage A, Thieuleux C, Emsley L, Copéret C. Solid-phase polarization matrixes for dynamic nuclear polarization from homogeneously distributed radicals in mesostructured hybrid silica materials. J Am Chem Soc 2013; 135:15459-66. [PMID: 23978152 DOI: 10.1021/ja405822h] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Mesoporous hybrid silica-organic materials containing homogeneously distributed stable mono- or dinitroxide radicals covalently bound to the silica surface were developed as polarization matrixes for solid-state dynamic nuclear polarization (DNP) NMR experiments. For TEMPO-containing materials impregnated with water or 1,1,2,2-tetrachloroethane, enhancement factors of up to 36 were obtained at ∼100 K and 9.4 T without the need for a glass-forming additive. We show that the homogeneous radical distribution and the subtle balance between the concentration of radical in the material and the fraction of radicals at a sufficient inter-radical distance to promote the cross-effect are the main determinants for the DNP enhancements we obtain. The material, as well as an analogue containing the poorly soluble biradical bTUrea, is used as a polarizing matrix for DNP NMR experiments of solutions containing alanine and pyruvic acid. The analyte is separated from the polarization matrix by simple filtration.
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Affiliation(s)
- David Gajan
- Department of Chemistry, ETH Zürich , CH-8093 Zürich, Switzerland
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53
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Zagdoun A, Casano G, Ouari O, Schwarzwälder M, Rossini AJ, Aussenac F, Yulikov M, Jeschke G, Copéret C, Lesage A, Tordo P, Emsley L. Large molecular weight nitroxide biradicals providing efficient dynamic nuclear polarization at temperatures up to 200 K. J Am Chem Soc 2013; 135:12790-7. [PMID: 23961876 DOI: 10.1021/ja405813t] [Citation(s) in RCA: 273] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
A series of seven functionalized nitroxide biradicals (the bTbK biradical and six derivatives) are investigated as exogenous polarization sources for dynamic nuclear polarization (DNP) solid-state NMR at 9.4 T and with ca. 100 K sample temperatures. The impact of electron relaxation times on the DNP enhancement (ε) is examined, and we observe that longer inversion recovery and phase memory relaxation times provide larger ε. All radicals are tested in both bulk 1,1,2,2-tetrachloroethane solutions and in mesoporous materials, and the difference in ε between the two cases is discussed. The impact of the sample temperature and magic angle spinning frequency on ε is investigated for several radicals each characterized by a range of electron relaxation times. In particular, TEKPol, a bulky derivative of bTbK with a molecular weight of 905 g·mol(-1), is presented. Its high-saturation factor makes it a very efficient polarizing agent for DNP, yielding unprecedented proton enhancements of over 200 in both bulk and materials samples at 9.4 T and 100 K. TEKPol also yields encouraging enhancements of 33 at 180 K and 12 at 200 K, suggesting that with the continued improvement of radicals large ε may be obtained at higher temperatures.
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Affiliation(s)
- Alexandre Zagdoun
- Centre de RMN à Très Hauts Champs, Institut de Sciences Analytiques, Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1), 69100 Villeurbanne, France
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54
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Sauvée C, Rosay M, Casano G, Aussenac F, Weber RT, Ouari O, Tordo P. Highly efficient, water-soluble polarizing agents for dynamic nuclear polarization at high frequency. Angew Chem Int Ed Engl 2013; 52:10858-61. [PMID: 23956072 DOI: 10.1002/anie.201304657] [Citation(s) in RCA: 328] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Indexed: 11/11/2022]
Affiliation(s)
- Claire Sauvée
- Aix-Marseille Université, CNRS, ICR UMR 7273, 13397 Marseille cedex 20 (France) http://sites.univ-provence.fr/srep/
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55
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Highly Efficient, Water-Soluble Polarizing Agents for Dynamic Nuclear Polarization at High Frequency. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201304657] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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56
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Affiliation(s)
- Manabu Abe
- Department of Chemistry, Graduate School of Science, Hiroshima University (HIRODAI), 1-3-1 Kagamiyama, Higashi-Hiroshima,
Hiroshima 739-8526, Japan
- Institute for Molecular Science (IMS), Okazaki, Aichi 444-8787,
Japan
- JST-CREST, 5
Sanbancho,
Chiyodaku, Tokyo 102-0075, Japan
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57
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Kavala M, Boča R, Dlháň L, Brezová V, Breza M, Kožíšek J, Fronc M, Herich P, Švorc L, Szolcsányi P. Preparation and Spectroscopic, Magnetic, and Electrochemical Studies of Mono-/Biradical TEMPO Derivatives. J Org Chem 2013; 78:6558-69. [DOI: 10.1021/jo400845m] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Miroslav Kavala
- Department
of Organic Chemistry, ‡Department of Inorganic Chemistry, §Department of Physical Chemistry, and ∥Department of
Analytical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského
9, SK-812 37 Bratislava, Slovakia
| | - Roman Boča
- Department
of Organic Chemistry, ‡Department of Inorganic Chemistry, §Department of Physical Chemistry, and ∥Department of
Analytical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského
9, SK-812 37 Bratislava, Slovakia
| | - Lubomír Dlháň
- Department
of Organic Chemistry, ‡Department of Inorganic Chemistry, §Department of Physical Chemistry, and ∥Department of
Analytical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského
9, SK-812 37 Bratislava, Slovakia
| | - Vlasta Brezová
- Department
of Organic Chemistry, ‡Department of Inorganic Chemistry, §Department of Physical Chemistry, and ∥Department of
Analytical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského
9, SK-812 37 Bratislava, Slovakia
| | - Martin Breza
- Department
of Organic Chemistry, ‡Department of Inorganic Chemistry, §Department of Physical Chemistry, and ∥Department of
Analytical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského
9, SK-812 37 Bratislava, Slovakia
| | - Jozef Kožíšek
- Department
of Organic Chemistry, ‡Department of Inorganic Chemistry, §Department of Physical Chemistry, and ∥Department of
Analytical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského
9, SK-812 37 Bratislava, Slovakia
| | - Marek Fronc
- Department
of Organic Chemistry, ‡Department of Inorganic Chemistry, §Department of Physical Chemistry, and ∥Department of
Analytical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského
9, SK-812 37 Bratislava, Slovakia
| | - Peter Herich
- Department
of Organic Chemistry, ‡Department of Inorganic Chemistry, §Department of Physical Chemistry, and ∥Department of
Analytical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského
9, SK-812 37 Bratislava, Slovakia
| | - Lubomír Švorc
- Department
of Organic Chemistry, ‡Department of Inorganic Chemistry, §Department of Physical Chemistry, and ∥Department of
Analytical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského
9, SK-812 37 Bratislava, Slovakia
| | - Peter Szolcsányi
- Department
of Organic Chemistry, ‡Department of Inorganic Chemistry, §Department of Physical Chemistry, and ∥Department of
Analytical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského
9, SK-812 37 Bratislava, Slovakia
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58
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Cheng CY, Han S. Dynamic Nuclear Polarization Methods in Solids and Solutions to Explore Membrane Proteins and Membrane Systems. Annu Rev Phys Chem 2013; 64:507-32. [DOI: 10.1146/annurev-physchem-040412-110028] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Membrane proteins regulate vital cellular processes, including signaling, ion transport, and vesicular trafficking. Obtaining experimental access to their structures, conformational fluctuations, orientations, locations, and hydration in membrane environments, as well as the lipid membrane properties, is critical to understanding their functions. Dynamic nuclear polarization (DNP) of frozen solids can dramatically boost the sensitivity of current solid-state nuclear magnetic resonance tools to enhance access to membrane protein structures in native membrane environments. Overhauser DNP in the solution state can map out the local and site-specific hydration dynamics landscape of membrane proteins and lipid membranes, critically complementing the structural and dynamics information obtained by electron paramagnetic resonance spectroscopy. Here, we provide an overview of how DNP methods in solids and solutions can significantly increase our understanding of membrane protein structures, dynamics, functions, and hydration in complex biological membrane environments.
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Affiliation(s)
- Chi-Yuan Cheng
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106
| | - Songi Han
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106
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59
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Liu Y, Villamena FA, Rockenbauer A, Song Y, Zweier JL. Structural factors controlling the spin-spin exchange coupling: EPR spectroscopic studies of highly asymmetric trityl-nitroxide biradicals. J Am Chem Soc 2013; 135:2350-6. [PMID: 23320522 DOI: 10.1021/ja311571v] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Highly asymmetric exchange-coupled biradicals, e.g., the trityl-nitroxides (TNs), possess particular magnetic properties that have opened new possibilities for their application in biophysical, physicochemical, and biological studies. In the present work, we investigated the effect of the linker length on the spin-spin coupling interaction (J) in TN biradicals using the newly synthesized biradicals CT02-GT, CT02-AT, CT02-VT, and CT02-PPT as well as the previously reported biradicals TNN14 and TN1. The results show that the magnitude of J can be easily tuned from ~4 G (conformer 1 in CT02-PPT) to >1200 G (in TNN14) by varying the linker separating the two radical moieties and changing the temperature. Computer simulations of EPR spectra were carried out to estimate J values of the TN biradicals directly. In addition to the spin-spin coupling interaction of TN biradicals, their g, hyperfine-splitting, and zero-field-splitting interactions were explored at low temperature (220 K). Our present study clearly shows that varying the spin-spin interaction as a function of linker distance and temperature provides an effective strategy for the development of new TN biradicals that can find wide applications in relevant fields.
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Affiliation(s)
- Yangping Liu
- Center for Biomedical EPR Spectroscopy and Imaging, The Davis Heart and Lung Research Institute, Division of Cardiovascular Medicine, Department of Internal Medicine, College of Medicine, The Ohio State University, Columbus, Ohio 43210, USA
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60
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Abstract
Nuclear magnetic resonance (NMR) spectroscopy is one of the most commonly used spectroscopic techniques to obtain information on the structure and dynamics of biological and chemical materials. A variety of samples can be studied including solutions, crystalline solids, powders and hydrated protein extracts. However, biological NMR spectroscopy is limited to concentrated samples, typically in the millimolar range, due to its intrinsic low sensitivity compared to other techniques such as fluorescence or electron paramagnetic resonance (EPR) spectroscopy.Dynamic nuclear polarization (DNP) is a method that increases the sensitivity of NMR by several orders of magnitude. It exploits a polarization transfer from unpaired electrons to neighboring nuclei which leads to an absolute increase of the signal-to-noise ratio (S/N). Consequently, biological samples with much lower concentrations can now be studied in hours or days compared to several weeks.This chapter will explain the different types of DNP enhanced NMR experiments, focusing primarily on solid-state magic angle spinning (MAS) DNP, its applications, and possible means of improvement.
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61
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Corzilius B, Smith AA, Griffin RG. Solid effect in magic angle spinning dynamic nuclear polarization. J Chem Phys 2012; 137:054201. [PMID: 22894339 DOI: 10.1063/1.4738761] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
For over five decades, the solid effect (SE) has been heavily utilized as a mechanism for performing dynamic nuclear polarization (DNP). Nevertheless, it has not found widespread application in contemporary, high magnetic field DNP experiments because SE enhancements display an ω(0)(-2) field dependence. In particular, for nominally forbidden zero and double quantum SE transitions to be partially allowed, it is necessary for mixing of adjacent nuclear spin states to occur, and this leads to the observed field dependence. However, recently we have improved our instrumentation and report here an enhancement of ε = 91 obtained with the organic radical trityl (OX063) in magic angle spinning experiments performed at 5 T and 80 K. This is a factor of 6-7 higher than previous values in the literature under similar conditions. Because the solid effect depends strongly on the microwave field strength, we attribute this large enhancement to larger microwave field strengths inside the sample volume, achieved with more efficient coupling of the gyrotron to the sample chamber. In addition, we develop a theoretical model to explain the dependence of the buildup rate of enhanced nuclear polarization and the steady-state enhancement on the microwave power. Buildup times and enhancements were measured as a function of (1)H concentration for both trityl and Gd-DOTA. Comparison of the results indicates that for trityl the initial polarization step is the slower, rate-determining step. However, for Gd-DOTA the spread of nuclear polarization via homonuclear (1)H spin diffusion is rate-limiting. Finally, we discuss the applicability of the solid effect at fields > 5 T and the requirements to address the unfavorable field dependence of the solid effect.
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Affiliation(s)
- Björn Corzilius
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
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62
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Rossini AJ, Zagdoun A, Hegner F, Schwarzwälder M, Gajan D, Copéret C, Lesage A, Emsley L. Dynamic nuclear polarization NMR spectroscopy of microcrystalline solids. J Am Chem Soc 2012; 134:16899-908. [PMID: 22967206 DOI: 10.1021/ja308135r] [Citation(s) in RCA: 197] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Dynamic nuclear polarization (DNP) solid-state NMR has been applied to powdered microcrystalline solids to obtain sensitivity enhancements on the order of 100. Glucose, sulfathiazole, and paracetamol were impregnated with bis-nitroxide biradical (bis-cyclohexyl-TEMPO-bisketal, bCTbK) solutions of organic solvents. The organic solvents were carefully chosen to be nonsolvents for the compounds, so that DNP-enhanced solid-state NMR spectra of the unaltered solids could be acquired. A theoretical model is presented that illustrates that for externally doped organic solids characterized by long spin-lattice relaxation times (T(1)((1)H) > 200 s), (1)H-(1)H spin diffusion can relay enhanced polarization over micrometer length scales yielding substantial DNP enhancements (ε). ε on the order of 60 are obtained for microcrystalline glucose and sulfathiazole at 9.4 T and with temperatures of ca. 105 K. The large gain in sensitivity enables the rapid acquisition of (13)C-(13)C correlation spectra at natural isotopic abundance. It is anticipated that this will be a general method for enhancing the sensitivity of solid-state NMR experiments of organic solids.
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Affiliation(s)
- Aaron J Rossini
- Centre de RMN a Tres Hauts Champs, Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1), 69100 Villeurbanne, France
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63
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Kiesewetter MK, Corzilius B, Smith AA, Griffin RG, Swager TM. Dynamic nuclear polarization with a water-soluble rigid biradical. J Am Chem Soc 2012; 134:4537-40. [PMID: 22372769 DOI: 10.1021/ja212054e] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new biradical polarizing agent, bTbtk-py, for dynamic nuclear polarization (DNP) experiments in aqueous media is reported. The synthesis is discussed in light of the requirements of the optimum, theoretical, biradical system. To date, the DNP NMR signal enhancement resulting from bTbtk-py is the largest of any biradical in the ideal glycerol/water solvent matrix, ε = 230. EPR and X-ray crystallography are used to characterize the molecule and suggest approaches for further optimizing the biradical distance and relative orientation.
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Affiliation(s)
- Matthew K Kiesewetter
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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64
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Bardelang D, Giorgi M, Hornebecq V, Stepanov A, Rizzato E, Zaman MB, Chan G, Ouari O, Tordo P. Perturbation induced formation of a 3D-network of microcrystals producing soft materials. RSC Adv 2012. [DOI: 10.1039/c2ra20208e] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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