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Chiliveri SC, Robertson AJ, Shen Y, Torchia DA, Bax A. Advances in NMR Spectroscopy of Weakly Aligned Biomolecular Systems. Chem Rev 2021; 122:9307-9330. [PMID: 34766756 DOI: 10.1021/acs.chemrev.1c00730] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The measurement and application of residual dipolar couplings (RDCs) in solution NMR studies of biological macromolecules has become well established over the past quarter of a century. Numerous methods for generating the requisite anisotropic orientational molecular distribution have been demonstrated, each with its specific strengths and weaknesses. In parallel, an enormous number of pulse schemes have been introduced to measure the many different types of RDCs, ranging from the most widely measured backbone amide 15N-1H RDCs, to 1H-1H RDCs and couplings between low-γ nuclei. Applications of RDCs range from structure validation and refinement to the determination of relative domain orientations, the measurement of backbone and domain motions, and de novo structure determination. Nevertheless, it appears that the power of the RDC methodology remains underutilized. This review aims to highlight the practical aspects of sample preparation and RDC measurement while describing some of the most straightforward applications that take advantage of the exceptionally precise information contained in such data. Some emphasis will be placed on more recent developments that enable the accurate measurement of RDCs in larger systems, which is key to the ongoing shift in focus of biological NMR spectroscopy from structure determination toward gaining improved understanding of how molecular flexibility drives protein function.
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Affiliation(s)
- Sai Chaitanya Chiliveri
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Angus J Robertson
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Yang Shen
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Dennis A Torchia
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Ad Bax
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States
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2
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Barut M, Kalkan Erdoğan M, Karakışla M, Saçak M. The hydrophilic modification of acrylic textile fibers by grafting of 2-hydroxyethyl methacrylate and investigation of the imparted properties. JOURNAL OF MACROMOLECULAR SCIENCE PART A-PURE AND APPLIED CHEMISTRY 2021. [DOI: 10.1080/10601325.2021.1982647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Merve Barut
- Department of Chemistry, Faculty of Science, Ankara University, Ankara, Turkey
| | | | - Meral Karakışla
- Department of Chemistry, Faculty of Science, Ankara University, Ankara, Turkey
| | - Mehmet Saçak
- Department of Chemistry, Faculty of Science, Ankara University, Ankara, Turkey
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3
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Sager E, Tzvetkova P, Gossert AD, Piechon P, Luy B. Determination of Configuration and Conformation of a Reserpine Derivative with Seven Stereogenic Centers Using Molecular Dynamics with RDC-Derived Tensorial Constraints*. Chemistry 2020; 26:14435-14444. [PMID: 32744785 PMCID: PMC7702126 DOI: 10.1002/chem.202002642] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 07/22/2020] [Indexed: 11/11/2022]
Abstract
NMR-based determination of the configuration of complex molecules containing many stereocenters is often not possible using traditional NOE data and coupling patterns. Making use of residual dipolar couplings (RDCs), we were able to determine the relative configuration of a natural product containing seven stereocenters, including a chiral amine lacking direct RDC data. To identify the correct relative configuration out of 32 possible ones, experimental RDCs were used in three different approaches for data interpretation: by fitting experimental data based singular value decomposition (SVD) using a single alignment tensor and either (i) a single conformer or (ii) multiple conformers, or alternatively (iii) using molecular dynamics simulations with tensorial orientational constraints (MDOC). Even though in all three approaches one and the same configuration could be selected and clear discrimination between possible configurations was achieved, the experimental data was not fully satisfied by the methods based on single tensor approaches. While these two approaches are faster, only MDOC is able to fully reproduce experimental results, as the obtained conformational ensemble adequately covers the conformational space necessary to describe the molecule with inherent flexibility.
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Affiliation(s)
- Emine Sager
- Institut für Organische ChemieKarlsruher Institut für Technologie (KIT)Fritz-Haber-Weg 676131KarlsruheGermany
- Novartis Pharma AGNovartis Institutes for Biomedical Research4002BaselSwitzerland
| | - Pavleta Tzvetkova
- Institut für Biologische Grenzflächen 4—Magnetische ResonanzKarlsruher Institut für Technologie (KIT)Postfach 364076021KarlsruheGermany
| | - Alvar D. Gossert
- Novartis Pharma AGNovartis Institutes for Biomedical Research4002BaselSwitzerland
- Institut für Molekularbiologie und BiophysikETH Zürich8093ZürichSwitzerland
| | - Philippe Piechon
- Novartis Pharma AGNovartis Institutes for Biomedical Research4002BaselSwitzerland
| | - Burkhard Luy
- Institut für Organische ChemieKarlsruher Institut für Technologie (KIT)Fritz-Haber-Weg 676131KarlsruheGermany
- Institut für Biologische Grenzflächen 4—Magnetische ResonanzKarlsruher Institut für Technologie (KIT)Postfach 364076021KarlsruheGermany
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4
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Relative configuration of micrograms of natural compounds using proton residual chemical shift anisotropy. Nat Commun 2020; 11:4372. [PMID: 32873801 PMCID: PMC7463026 DOI: 10.1038/s41467-020-18093-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 07/28/2020] [Indexed: 01/12/2023] Open
Abstract
3D molecular structure determination is a challenge for organic compounds or natural products available in minute amounts. Proton/proton and proton/carbon correlations yield the constitution. J couplings and NOEs oftentimes supported by one-bond 1H,13C residual dipolar couplings (RDCs) or by 13C residual chemical shift anisotropies (RCSAs) provide the relative configuration. However, these RDCs or carbon RCSAs rely on 1% natural abundance of 13C preventing their use for compounds available only in quantities of a few 10’s of µgs. By contrast, 1H RCSAs provide similar information on spatial orientation of structural moieties within a molecule, while using the abundant 1H spin. Herein, 1H RCSAs are accurately measured using constrained aligning gels or liquid crystals and applied to the 3D structural determination of molecules with varying complexities. Even more, deuterated alignment media allow the elucidation of the relative configuration of around 35 µg of a briarane compound isolated from Briareum asbestinum. Determination of 3D molecular structures remains challenging for natural products or organic compounds available in minute amounts. Here, the authors determine the structure of complex molecules, including few micrograms of briarane B-3 isolated from Briareum asbestinums, through measurement of 1H residual chemical shift anisotropy.
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Köck M, Reggelin M, Immel S. The Advanced Floating Chirality Distance Geometry Approach-How Anisotropic NMR Parameters Can Support the Determination of the Relative Configuration of Natural Products. Mar Drugs 2020; 18:md18060330. [PMID: 32599876 PMCID: PMC7344786 DOI: 10.3390/md18060330] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/16/2020] [Accepted: 06/18/2020] [Indexed: 11/16/2022] Open
Abstract
The configurational analysis of complex natural products by NMR spectroscopy is still a challenging task. The assignment of the relative configuration is usually carried out by analysis of interproton distances from NOESY or ROESY spectra (qualitative or quantitative) and scalar (J) couplings. About 15 years ago, residual dipolar couplings (RDCs) were introduced as a tool for the configurational determination of small organic molecules. In contrast to NOEs/ROEs which are local parameters (distances up to 400 pm can be detected for small organic molecules), RDCs are global parameters which allow to obtain structural information also from long-range relationships. RDCs have the disadvantage that the sample needs a setup in an alignment medium in order to obtain the required anisotropic environment. Here, we will discuss the configurational analysis of five complex natural products: axinellamine A (1), tetrabromostyloguanidine (2), 3,7-epi-massadine chloride (3), tubocurarine (4), and vincristine (5). Compounds 1-3 are marine natural products whereas 4 and 5 are from terrestrial sources. The chosen examples will carefully work out the limitations of NOEs/ROEs in the configurational analysis of natural products and will also provide an outlook on the information obtained from RDCs.
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Affiliation(s)
- Matthias Köck
- Alfred-Wegener-Institut für Polar-und Meeresforschung in der Helmholtz-Gemeinschaft, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Michael Reggelin
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie, Technische Universität Darmstadt, Alarich-Weiss-Straße 4, 64287 Darmstadt, Germany
| | - Stefan Immel
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie, Technische Universität Darmstadt, Alarich-Weiss-Straße 4, 64287 Darmstadt, Germany
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6
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Ma ZK, Han XY, Liu H, Ji JC, Qin SY, Li XD, Lei X. Lyotropic liquid crystal to measure residual dipolar couplings in dimethyl sulfoxide based on modified cellulose nanocrystals. NEW J CHEM 2020. [DOI: 10.1039/c9nj06031f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel lyotropic liquid crystal was developed for the measurement of RDCs of organic molecules with no background signals.
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Affiliation(s)
- Zong-Kai Ma
- Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education & Hubei Key Laboratory of Catalysis and Materials Science
- South-Central University for Nationalities
- Wuhan 430074
- P. R. China
| | - Xiao-Yang Han
- School of Pharmaceutical Sciences
- South-Central University for Nationalities
- Wuhan
- P. R. China
| | - Han Liu
- School of Pharmaceutical Sciences
- South-Central University for Nationalities
- Wuhan
- P. R. China
| | - Jia-Cheng Ji
- School of Pharmaceutical Sciences
- South-Central University for Nationalities
- Wuhan
- P. R. China
| | - Si-Yong Qin
- Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education & Hubei Key Laboratory of Catalysis and Materials Science
- South-Central University for Nationalities
- Wuhan 430074
- P. R. China
| | - Xiang-Dan Li
- Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education & Hubei Key Laboratory of Catalysis and Materials Science
- South-Central University for Nationalities
- Wuhan 430074
- P. R. China
| | - Xinxiang Lei
- School of Pharmaceutical Sciences
- South-Central University for Nationalities
- Wuhan
- P. R. China
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7
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Tzvetkova P, Sternberg U, Gloge T, Navarro-Vázquez A, Luy B. Configuration determination by residual dipolar couplings: accessing the full conformational space by molecular dynamics with tensorial constraints. Chem Sci 2019; 10:8774-8791. [PMID: 31803450 PMCID: PMC6849632 DOI: 10.1039/c9sc01084j] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 07/19/2019] [Indexed: 12/27/2022] Open
Abstract
Residual dipolar couplings (RDCs) and other residual anisotropic NMR parameters provide valuable structural information of high quality and quantity, bringing detailed structural models of flexible molecules in solution in reach. The corresponding data interpretation so far is directly or indirectly based on the concept of a molecular alignment tensor, which, however, is ill-defined for flexible molecules. The concept is typically applied to a single or a small set of lowest energy structures, ignoring the effect of vibrational averaging. Here, we introduce an entirely different approach based on time averaged molecular dynamics with dipolar couplings as tensorial orientational restraints that can be used to solve structural problems in molecules of any size without the need of introducing an explicit molecular alignment tensor into the computation. RDC restraints are represented by their full 3D interaction tensor in the laboratory frame, for which pseudo forces are calculated using a secular dipolar Hamiltonian as the target. The resulting rotational averaging of each individual tensorial restraint leads to structural ensembles that best fulfil the experimental data. Using one-bond RDCs, the approach has been implemented in the force field procedures of the program COSMOS and extensively tested. A concise theoretical introduction, including the special treatment of force fields for stable and fast MD simulations, as well as applications regarding configurational analyses of small to medium-sized organic molecules with different degrees of flexibility, is given. The observed results are discussed in detail.
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Affiliation(s)
- Pavleta Tzvetkova
- Institute of Organic Chemistry and Institute for Biological Interfaces 4 - Magnetic Resonance , Karlsruhe Institute of Technology (KIT) , Fritz-Haber-Weg 6 , 76131 Karlsruhe , Germany . ;
| | - Ulrich Sternberg
- Institute of Organic Chemistry and Institute for Biological Interfaces 4 - Magnetic Resonance , Karlsruhe Institute of Technology (KIT) , Fritz-Haber-Weg 6 , 76131 Karlsruhe , Germany . ;
| | - Thomas Gloge
- Institute of Organic Chemistry and Institute for Biological Interfaces 4 - Magnetic Resonance , Karlsruhe Institute of Technology (KIT) , Fritz-Haber-Weg 6 , 76131 Karlsruhe , Germany . ;
| | - Armando Navarro-Vázquez
- Institute of Organic Chemistry and Institute for Biological Interfaces 4 - Magnetic Resonance , Karlsruhe Institute of Technology (KIT) , Fritz-Haber-Weg 6 , 76131 Karlsruhe , Germany . ;
| | - Burkhard Luy
- Institute of Organic Chemistry and Institute for Biological Interfaces 4 - Magnetic Resonance , Karlsruhe Institute of Technology (KIT) , Fritz-Haber-Weg 6 , 76131 Karlsruhe , Germany . ;
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8
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Carvalho DS, da Silva DGB, Hallwass F, Navarro-Vázquez A. Chemically cross-linked polyacrylonitrile. A DMSO compatible NMR alignment medium for measurement of residual dipolar couplings and residual chemical shift anisotropies. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 302:21-27. [PMID: 30933840 DOI: 10.1016/j.jmr.2019.03.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 03/09/2019] [Accepted: 03/14/2019] [Indexed: 06/09/2023]
Abstract
Chemically cross-linked polyacrylontrile polymer gels, have been prepared as an alignment medium compatible with DMSO-d6. These gels allow measurement of residual dipolar couplings (RDCs) and residual chemical shift anisotropies (RCSAs) with good accuracy as tested with brucine and α-santonin natural compounds. The gels can be reversibly compressed allowing easy measurement of RCSAs. They also present good physical homogeneity, clean HSQC spectra with little background 1H signals, and allow unambiguous referencing of 13C spectra for RCSA extraction.
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Affiliation(s)
- Daiane S Carvalho
- Universidade Federal de Pernambuco, Departamento de Química Fundamental, CCEN, Recife, Pernambuco 50670-901, Brazil
| | - Danilo G B da Silva
- Universidade Federal de Pernambuco, Departamento de Química Fundamental, CCEN, Recife, Pernambuco 50670-901, Brazil
| | - Fernando Hallwass
- Universidade Federal de Pernambuco, Departamento de Química Fundamental, CCEN, Recife, Pernambuco 50670-901, Brazil
| | - Armando Navarro-Vázquez
- Universidade Federal de Pernambuco, Departamento de Química Fundamental, CCEN, Recife, Pernambuco 50670-901, Brazil.
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9
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Reller M, Wesp S, Koos MRM, Reggelin M, Luy B. Biphasic Liquid Crystal and the Simultaneous Measurement of Isotropic and Anisotropic Parameters by Spatially Resolved NMR Spectroscopy. Chemistry 2017. [DOI: 10.1002/chem.201702126] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Malin Reller
- Institut für Organische Chemie and Institut für Biologische Grenzflächen 4 - Magnetische Resonanz; Karlsruher Institut für Technologie (KIT); Fritz-Haber-Weg 6 76131 Karlsruhe Germany
| | - Svenja Wesp
- Organische Chemie; Technische Universität Darmstadt; Alarich-Weiss Str. 4 64287 Darmstadt Germany
| | - Martin R. M. Koos
- Institut für Organische Chemie and Institut für Biologische Grenzflächen 4 - Magnetische Resonanz; Karlsruher Institut für Technologie (KIT); Fritz-Haber-Weg 6 76131 Karlsruhe Germany
| | - Michael Reggelin
- Organische Chemie; Technische Universität Darmstadt; Alarich-Weiss Str. 4 64287 Darmstadt Germany
| | - Burkhard Luy
- Institut für Organische Chemie and Institut für Biologische Grenzflächen 4 - Magnetische Resonanz; Karlsruher Institut für Technologie (KIT); Fritz-Haber-Weg 6 76131 Karlsruhe Germany
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10
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Tzvetkova P, Luy B. Q.E.COSY: determining sign and size of small deuterium residual quadrupolar couplings using an extended E.COSY principle. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2016; 54:351-357. [PMID: 26763050 DOI: 10.1002/mrc.4386] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 09/30/2015] [Accepted: 10/23/2015] [Indexed: 06/05/2023]
Abstract
Residual quadrupolar couplings contain important structural information comparable with residual dipolar couplings. However, the measurement of sign and size of especially small residual quadrupolar couplings is difficult. Here, we present an extension of the E.COSY principle to spin systems consisting of a Spin 1 coupled to a spin ½ nucleus, which allows the determination of the sign of the quadrupolar coupling of the Spin 1 nucleus relative to the heteronuclear coupling between the spins. The so-called Q.E.COSY approach is demonstrated with its sign-sensitivity using variable angle NMR, stretched gels and liquid crystalline phases applied to various CD and CD3 groups. Especially the sign-sensitive measurement of residual quadrupolar couplings that remain unresolved in conventional deuterium 1D spectra is shown.
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Affiliation(s)
- Pavleta Tzvetkova
- Institute of Organic Chemistry and Institute for Biological Interfaces 4 - Magnetic Resonance, Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany
| | - Burkhard Luy
- Institute of Organic Chemistry and Institute for Biological Interfaces 4 - Magnetic Resonance, Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany
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11
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Zong W, Li GW, Cao JM, Lei X, Hu ML, Sun H, Griesinger C, Tan RX. An Alignment Medium for Measuring Residual Dipolar Couplings in Pure DMSO: Liquid Crystals from Graphene Oxide Grafted with Polymer Brushes. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201511435] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Wen Zong
- College of Chemistry & Materials Engineering; Wenzhou University; Wenzhou 325035 P.R. China
| | - Gao-Wei Li
- Institute of Functional Biomolecules; State Key Laboratory of Pharmaceutical Biotechnology; Nanjing University; Nanjing 210093 P.R. China
| | - Jiang-Ming Cao
- Institute of Functional Biomolecules; State Key Laboratory of Pharmaceutical Biotechnology; Nanjing University; Nanjing 210093 P.R. China
| | - Xinxiang Lei
- College of Chemistry & Materials Engineering; Wenzhou University; Wenzhou 325035 P.R. China
| | - Mao-Lin Hu
- College of Chemistry & Materials Engineering; Wenzhou University; Wenzhou 325035 P.R. China
| | - Han Sun
- Leibniz-Institut für Molekulare Pharmakologie (FMP); Robert-Roessle-Strasse 10 13125 Berlin Germany
| | - Christian Griesinger
- Department of NMR-based Structural Biology; Max Planck Institute for Biophysical Chemistry; 37077 Göttingen Germany
| | - Ren Xiang Tan
- Institute of Functional Biomolecules; State Key Laboratory of Pharmaceutical Biotechnology; Nanjing University; Nanjing 210093 P.R. China
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12
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Zong W, Li GW, Cao JM, Lei X, Hu ML, Sun H, Griesinger C, Tan RX. An Alignment Medium for Measuring Residual Dipolar Couplings in Pure DMSO: Liquid Crystals from Graphene Oxide Grafted with Polymer Brushes. Angew Chem Int Ed Engl 2016; 55:3690-3. [DOI: 10.1002/anie.201511435] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Indexed: 11/10/2022]
Affiliation(s)
- Wen Zong
- College of Chemistry & Materials Engineering; Wenzhou University; Wenzhou 325035 P.R. China
| | - Gao-Wei Li
- Institute of Functional Biomolecules; State Key Laboratory of Pharmaceutical Biotechnology; Nanjing University; Nanjing 210093 P.R. China
| | - Jiang-Ming Cao
- Institute of Functional Biomolecules; State Key Laboratory of Pharmaceutical Biotechnology; Nanjing University; Nanjing 210093 P.R. China
| | - Xinxiang Lei
- College of Chemistry & Materials Engineering; Wenzhou University; Wenzhou 325035 P.R. China
| | - Mao-Lin Hu
- College of Chemistry & Materials Engineering; Wenzhou University; Wenzhou 325035 P.R. China
| | - Han Sun
- Leibniz-Institut für Molekulare Pharmakologie (FMP); Robert-Roessle-Strasse 10 13125 Berlin Germany
| | - Christian Griesinger
- Department of NMR-based Structural Biology; Max Planck Institute for Biophysical Chemistry; 37077 Göttingen Germany
| | - Ren Xiang Tan
- Institute of Functional Biomolecules; State Key Laboratory of Pharmaceutical Biotechnology; Nanjing University; Nanjing 210093 P.R. China
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Merle C, Kummerlöwe G, Freudenberger JC, Halbach F, Stöwer W, Gostomski CLV, Höpfner J, Beskers T, Wilhelm M, Luy B. Crosslinked Poly(ethylene oxide) as a Versatile Alignment Medium for the Measurement of Residual Anisotropic NMR Parameters. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201301929] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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14
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Merle C, Kummerlöwe G, Freudenberger JC, Halbach F, Stöwer W, Gostomski CLV, Höpfner J, Beskers T, Wilhelm M, Luy B. Crosslinked Poly(ethylene oxide) as a Versatile Alignment Medium for the Measurement of Residual Anisotropic NMR Parameters. Angew Chem Int Ed Engl 2013; 52:10309-12. [DOI: 10.1002/anie.201301929] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 06/26/2013] [Indexed: 11/07/2022]
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15
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Kaden P, Freudenberger JC, Luy B. Noncovalently and covalently cross-linked polyurethane gels as alignment media and the suppression of residual polymer signals using diffusion-filtered spectroscopy. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2012; 50 Suppl 1:S22-S28. [PMID: 23280657 DOI: 10.1002/mrc.3887] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 08/03/2012] [Accepted: 09/20/2012] [Indexed: 06/01/2023]
Abstract
With polyurethane (PU), a novel alignment medium for organic solvents is introduced and characterized, which is very robust and easy to produce on a large scale. Linear PU already constitutes an elastomer gel with several solvents based on its ability to form hydrogen bonds. Covalent cross-linking of the polymer with accelerated electrons provides an alignment medium with different properties. However, PU exhibits a number of undesired polymer signals in corresponding spectra, which ideally have to be removed spectroscopically. Within this context, we demonstrate the applicability of diffusion-filtered experiments for removal of the polymer signals. Example spectra for the usefulness of PU alignment media are provided for the common test molecules strychnine and norcamphor.
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Affiliation(s)
- Peter Kaden
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal, Postfach 3640, 76021 Karlsruhe, Germany
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