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Sugiki T, Ito A, Hatanaka Y, Tsukamoto M, Murata T, Miyanishi K, Kagawa A, Fujiwara T, Kitagawa M, Morita Y, Negoro M. Real-time monitoring of enzyme-catalyzed phosphoribosylation of anti-influenza prodrug favipiravir by time-lapse nuclear magnetic resonance spectroscopy. NMR IN BIOMEDICINE 2023; 36:e4888. [PMID: 36468685 DOI: 10.1002/nbm.4888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 12/01/2022] [Accepted: 12/02/2022] [Indexed: 06/17/2023]
Abstract
Favipiravir (brand name Avigan), a widely known anti-influenza prodrug, is metabolized by endogenous enzymes of host cells to generate the active form, which exerts inhibition of viral RNA-dependent RNA polymerase activity; first, favipiravir is converted to its phosphoribosylated form, favipiravir-ribofuranosyl-5'-monophosphate (favipiravir-RMP), by hypoxanthine-guanine phosphoribosyltransferase (HGPRT). Because this phosphoribosylation reaction is the rate-determining step in the generation of the active metabolite, quantitative and real-time monitoring of the HGPRT-catalyzed reaction is essential to understanding the pharmacokinetics of favipiravir. However, assay methods enabling such monitoring have not been established. 19 F- or 31 P-based nuclear magnetic resonance (NMR) are powerful techniques for observation of intermolecular interactions, chemical reactions, and metabolism of molecules of interest, given that NMR signals of the heteronuclei sensitively reflect changes in the chemical environment of these moieties. Here, we demonstrated direct, sensitive, target-selective, nondestructive, and real-time observation of HGPRT-catalyzed conversion of favipiravir to favipiravir-RMP by performing time-lapse 19 F-NMR monitoring of the fluorine atom of favipiravir. In addition, we showed that 31 P-NMR can be used for real-time observation of the identical reaction by monitoring phosphorus atoms of the phosphoribosyl group of favipiravir-RMP and of the pyrophosphate product of that reaction. Furthermore, we demonstrated that NMR approaches permit the determination of general parameters of enzymatic activity such as Vmax and Km . This method not only can be widely employed in enzyme assays, but also may be of use in the screening and development of new favipiravir-analog antiviral prodrugs that can be phosphoribosylated more efficiently by HGPRT, which would increase the intracellular concentration of the drug's active form. The techniques demonstrated in this study would allow more detailed investigation of the pharmacokinetics of fluorinated drugs, and might significantly contribute to opening new avenues for widespread pharmaceutical studies.
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Affiliation(s)
| | - Akihiro Ito
- Analytical Instrument Facility, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
| | - Yuko Hatanaka
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan
- Center for Quantum Information and Quantum Biology (QIQB), Osaka University, Toyonaka, Osaka, Japan
| | - Masaki Tsukamoto
- Graduate School of Informatics, Nagoya University, Nagoya, Aichi, Japan
| | - Tsuyoshi Murata
- Faculty of Engineering, Aichi Institute of Technology, Yakusa, Toyota, Aichi, Japan
| | - Koichiro Miyanishi
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan
- Center for Quantum Information and Quantum Biology (QIQB), Osaka University, Toyonaka, Osaka, Japan
| | - Akinori Kagawa
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan
- Center for Quantum Information and Quantum Biology (QIQB), Osaka University, Toyonaka, Osaka, Japan
| | - Toshimichi Fujiwara
- Institute for Protein Research, Osaka University, Osaka, Japan
- Center for Quantum Information and Quantum Biology (QIQB), Osaka University, Toyonaka, Osaka, Japan
| | - Masahiro Kitagawa
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan
- Center for Quantum Information and Quantum Biology (QIQB), Osaka University, Toyonaka, Osaka, Japan
| | - Yasushi Morita
- Faculty of Engineering, Aichi Institute of Technology, Yakusa, Toyota, Aichi, Japan
| | - Makoto Negoro
- Center for Quantum Information and Quantum Biology (QIQB), Osaka University, Toyonaka, Osaka, Japan
- Institute for Quantum Life Science, National Institute for Quantum and Radiological Science and Technology, Chiba, Japan
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Mandal R, Pham P, Hilty C. Screening of Protein-Ligand Binding Using a SABRE Hyperpolarized Reporter. Anal Chem 2022; 94:11375-11381. [PMID: 35921650 DOI: 10.1021/acs.analchem.2c02250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hyperpolarization through signal amplification by reversible exchange (SABRE) provides a facile means to enhance nuclear magnetic resonance (NMR) signals of small molecules containing an N-heterocycle or other binding site for a polarization transfer catalyst. A purpose-designed reporter ligand, which is capable of binding both to a target protein and to the catalyst, makes the sensitivity enhancement by this technique compatible with the measurement of a range of biomolecular interactions. The 1H polarization of the reporter ligand 4-amidinopyridine, which is targeting trypsin, is used to screen ligands that are not themselves hyperpolarizable by SABRE. The respective protein-ligand dissociation constants (KD) are determined by an observed change in the R2 relaxation rate of the reporter. A calculation of expected signal changes indicates that the accessible ligand KD values extend over several orders of magnitude, while the concentrations of target proteins and ligands can be reduced considering the sensitivity gains from hyperpolarization. In general, the design of a single, weakly binding ligand for a target protein enables the use of SABRE hyperpolarization for ligand screening or other biophysical studies involving macromolecular interactions.
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Affiliation(s)
- Ratnamala Mandal
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77843, United States
| | - Pierce Pham
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77843, United States
| | - Christian Hilty
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77843, United States
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Mandal R, Pham P, Hilty C. Characterization of protein-ligand interactions by SABRE. Chem Sci 2021; 12:12950-12958. [PMID: 34745525 PMCID: PMC8515190 DOI: 10.1039/d1sc03404a] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 08/18/2021] [Indexed: 12/11/2022] Open
Abstract
Nuclear spin hyperpolarization through signal amplification by reversible exchange (SABRE), the non-hydrogenative version of para-hydrogen induced polarization, is demonstrated to enhance sensitivity for the detection of biomacromolecular interactions. A target ligand for the enzyme trypsin includes the binding motif for the protein, and at a distant location a heterocyclic nitrogen atom for interacting with a SABRE polarization transfer catalyst. This molecule, 4-amidinopyridine, is hyperpolarized with 50% para-hydrogen to yield enhancement values ranging from −87 and −34 in the ortho and meta positions of the heterocyclic nitrogen, to −230 and −110, for different solution conditions. Ligand binding is identified by flow-NMR, in a two-step process that separately optimizes the polarization transfer in methanol while detecting the interaction in a predominantly aqueous medium. A single scan Carr–Purcell–Meiboom–Gill (CPMG) experiment identifies binding by the change in R2 relaxation rate. The SABRE hyperpolarization technique provides a cost effective means to enhance NMR of biological systems, for the identification of protein–ligand interactions and other applications. Protein–ligand binding interactions are characterized by the para-H2 based hyperpolarization technique SABRE and flow-NMR. Binding to the protein is identified by R2 change of a ligand first interacting with the Ir polarization transfer catalyst.![]()
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Affiliation(s)
- Ratnamala Mandal
- Department of Chemistry, Texas A&M University 3255 TAMU College Station TX 77843 USA
| | - Pierce Pham
- Department of Chemistry, Texas A&M University 3255 TAMU College Station TX 77843 USA
| | - Christian Hilty
- Department of Chemistry, Texas A&M University 3255 TAMU College Station TX 77843 USA
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Cañada FJ, Canales Á, Valverde P, de Toro BF, Martínez-Orts M, Phillips PO, Pereda A. Conformational and Structural characterization of carbohydrates and their interactions studied by NMR. Curr Med Chem 2021; 29:1147-1172. [PMID: 34225601 DOI: 10.2174/0929867328666210705154046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 04/30/2021] [Accepted: 05/12/2021] [Indexed: 11/22/2022]
Abstract
Carbohydrates, either free or as glycans conjugated with other biomolecules, participate in many essential biological processes. Their apparent simplicity in terms of chemical functionality hides an extraordinary diversity and structural complexity. Deeply deciphering at the atomic level their structures is essential to understand their biological function and activities, but it is still a challenging task in need of complementary approaches and no generalized procedures are available to address the study of such complex, natural glycans. The versatility of Nuclear Magnetic Resonance spectroscopy (NMR) often makes it the preferred choice to study glycans and carbohydrates in solution media. The most basic NMR parameters, namely chemical shifts, coupling constants and nuclear Overhauser effects, allow defining short or repetitive chain sequences and characterize their structures and local geometries either in the free state or when interacting with other biomolecules, rendering additional information on the molecular recognition processes. The increased accessibility to carbohydrate molecules extensively or selectively labeled with 13C boosts the resolution and detail that analyzed glycan structures can reach. In turn, structural information derived from NMR, complemented with molecular modeling and theoretical calculations can also provide dynamic information on the conformational flexibility of carbohydrate structures. Furthermore, using partially oriented media or paramagnetic perturbations, it has been possible to introduce additional long-range observables rendering structural information on longer and branched glycan chains. In this review, we provide examples of these studies and an overview of the recent and most relevant NMR applications in the glycobiology field.
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Affiliation(s)
- Francisco Javier Cañada
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas Margarita Salas, CSIC, 28040 Madrid, Spain
| | - Ángeles Canales
- Departamento de Química Orgánica I, Facultad Ciencias Químicas, Universidad Complutense de Madrid, Avd. Complutense s/n, C.P. 28040 Madrid, Spain
| | - Pablo Valverde
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas Margarita Salas, CSIC, 28040 Madrid, Spain
| | - Beatriz Fernández de Toro
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas Margarita Salas, CSIC, 28040 Madrid, Spain
| | - Mónica Martínez-Orts
- Departamento de Química Orgánica I, Facultad Ciencias Químicas, Universidad Complutense de Madrid, Avd. Complutense s/n, C.P. 28040 Madrid, Spain
| | - Paola Oquist Phillips
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas Margarita Salas, CSIC, 28040 Madrid, Spain
| | - Amaia Pereda
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas Margarita Salas, CSIC, 28040 Madrid, Spain
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Kress T, Che K, Epasto L, Kozak F, Negroni M, Olsen G, Selimovic A, Kurzbach D. A novel sample handling system for dissolution dynamic nuclear polarization experiments. MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2021; 2:387-394. [PMID: 37904780 PMCID: PMC10539747 DOI: 10.5194/mr-2-387-2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 05/19/2021] [Indexed: 11/01/2023]
Abstract
We present a system for facilitated sample vitrification, melting, and transfer in dissolution dynamic nuclear polarization (DDNP) experiments. In DDNP, a sample is typically hyperpolarized at cryogenic temperatures before dissolution with hot solvent and transfer to a nuclear magnetic resonance (NMR) spectrometer for detection in the liquid state. The resulting signal enhancements can exceed 4 orders of magnitude. However, the sudden temperature jump from cryogenic temperatures close to 1 K to ambient conditions imposes a particular challenge. It is necessary to rapidly melt the sample to avoid a prohibitively fast decay of hyperpolarization. Here, we demonstrate a sample dissolution method that facilitates the temperature jump by eliminating the need to open the cryostat used to cool the sample. This is achieved by inserting the sample through an airlock in combination with a dedicated dissolution system that is inserted through the same airlock shortly before the melting event. The advantages are threefold: (1) the cryostat can be operated continuously at low temperatures. (2) The melting process is rapid as no pressurization steps of the cryostat are required. (3) Blockages of the dissolution system due to freezing of solvents during melting and transfer are minimized.
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Affiliation(s)
- Thomas Kress
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road,
Cambridge CB2 1EW, UK
| | - Kateryna Che
- Faculty of Chemistry, Institute of Biological
Chemistry, University of Vienna, Währinger Str. 38, Vienna, Austria
| | - Ludovica M. Epasto
- Faculty of Chemistry, Institute of Biological
Chemistry, University of Vienna, Währinger Str. 38, Vienna, Austria
| | - Fanny Kozak
- Faculty of Chemistry, Institute of Biological
Chemistry, University of Vienna, Währinger Str. 38, Vienna, Austria
| | - Mattia Negroni
- Faculty of Chemistry, Institute of Biological
Chemistry, University of Vienna, Währinger Str. 38, Vienna, Austria
| | - Gregory L. Olsen
- Faculty of Chemistry, Institute of Biological
Chemistry, University of Vienna, Währinger Str. 38, Vienna, Austria
| | - Albina Selimovic
- Faculty of Chemistry, Institute of Biological
Chemistry, University of Vienna, Währinger Str. 38, Vienna, Austria
| | - Dennis Kurzbach
- Faculty of Chemistry, Institute of Biological
Chemistry, University of Vienna, Währinger Str. 38, Vienna, Austria
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Wang Y, Hilty C. Amplification of Nuclear Overhauser Effect Signals by Hyperpolarization for Screening of Ligand Binding to Immobilized Target Proteins. Anal Chem 2020; 92:13718-13723. [PMID: 32897681 DOI: 10.1021/acs.analchem.0c01071] [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
Immobilization of a target protein enhances the cross-relaxation rates for transfer of nuclear spin polarization but reduces the accessible target concentration. Hyperpolarization of ligand spins by dissolution dynamic nuclear polarization (D-DNP) is shown to increase sensitivity for observing the intraligand nuclear Overhauser effect (NOE). This effect, also known as the transferred NOE (trNOE), can be used for detection of binding and for obtaining binding-related structural information. The measurement of hyperpolarized trNOE signals is demonstrated for the ligand 4'-hydroxyazobenzene-2-carboxylic acid interacting with avidin protein immobilized on polystyrene beads. In a sample containing 63.5 μM ligands and 0.83 μM accessible protein binding sites, the signal enhancement provided by D-DNP leads to single-scan detection of the NOE buildup, despite that this signal peaks at only 2% of the total ligand signal. These buildup curves allow the confirmation of binding through a change in the sign of the NOE and the quantitative determination of cross-relaxation rates. The combination of the D-DNP technique and protein immobilization may facilitate the identification of intraligand NOEs in ligand screening for drug discovery. The same method may be applied to in vivo characterization of ligand interactions with cell surface proteins.
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Affiliation(s)
- Yunyi Wang
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77843, United States
| | - Christian Hilty
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77843, United States
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7
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Wang Y, Kim J, Hilty C. Determination of protein-ligand binding modes using fast multi-dimensional NMR with hyperpolarization. Chem Sci 2020; 11:5935-5943. [PMID: 32874513 PMCID: PMC7441707 DOI: 10.1039/d0sc00266f] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 05/05/2020] [Indexed: 11/21/2022] Open
Abstract
Elucidation of small molecule-protein interactions provides essential information for understanding biological processes such as cellular signaling, as well as for rational drug development. Here, multi-dimensional NMR with sensitivity enhancement by dissolution dynamic nuclear polarization (D-DNP) is shown to allow the determination of the binding epitope of folic acid when complexed with the target dihydrofolate reductase. Protein signals are selectively enhanced by polarization transfer from the hyperpolarized ligand. A pseudo three-dimensional data acquisition with ligand-side Hadamard encoding results in protein-side [13C, 1H] chemical shift correlations that contain intermolecular nuclear Overhauser effect (NOE) information. A scoring function based on this data is used to select pre-docked ligand poses. The top five poses are within 0.76 Å root-mean-square deviation from a reference structure for the encoded five protons, showing improvements compared with the poses selected by an energy-based scoring function without experimental inputs. The sensitivity enhancement provided by the D-DNP combined with multi-dimensional NMR increases the speed and potentially the selectivity of structure elucidation of ligand binding epitopes.
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Affiliation(s)
- Yunyi Wang
- Department of Chemistry , Texas A&M University , 3255 TAMU , College Station , TX 77843 , USA .
| | - Jihyun Kim
- Department of Chemistry , Texas A&M University , 3255 TAMU , College Station , TX 77843 , USA .
| | - Christian Hilty
- Department of Chemistry , Texas A&M University , 3255 TAMU , College Station , TX 77843 , USA .
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8
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Olsen GL, Szekely O, Mateos B, Kadeřávek P, Ferrage F, Konrat R, Pierattelli R, Felli IC, Bodenhausen G, Kurzbach D, Frydman L. Sensitivity-enhanced three-dimensional and carbon-detected two-dimensional NMR of proteins using hyperpolarized water. JOURNAL OF BIOMOLECULAR NMR 2020; 74:161-171. [PMID: 32040802 PMCID: PMC7080779 DOI: 10.1007/s10858-020-00301-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 01/27/2020] [Indexed: 05/11/2023]
Abstract
Signal enhancements of up to two orders of magnitude in protein NMR can be achieved by employing HDO as a vector to introduce hyperpolarization into folded or intrinsically disordered proteins. In this approach, hyperpolarized HDO produced by dissolution-dynamic nuclear polarization (D-DNP) is mixed with a protein solution waiting in a high-field NMR spectrometer, whereupon amide proton exchange and nuclear Overhauser effects (NOE) transfer hyperpolarization to the protein and enable acquisition of a signal-enhanced high-resolution spectrum. To date, the use of this strategy has been limited to 1D and 1H-15N 2D correlation experiments. Here we introduce 2D 13C-detected D-DNP, to reduce exchange-induced broadening and other relaxation penalties that can adversely affect proton-detected D-DNP experiments. We also introduce hyperpolarized 3D spectroscopy, opening the possibility of D-DNP studies of larger proteins and IDPs, where assignment and residue-specific investigation may be impeded by spectral crowding. The signal enhancements obtained depend in particular on the rates of chemical and magnetic exchange of the observed residues, thus resulting in non-uniform 'hyperpolarization-selective' signal enhancements. The resulting spectral sparsity, however, makes it possible to resolve and monitor individual amino acids in IDPs of over 200 residues at acquisition times of just over a minute. We apply the proposed experiments to two model systems: the compactly folded protein ubiquitin, and the intrinsically disordered protein (IDP) osteopontin (OPN).
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Affiliation(s)
- Gregory L Olsen
- Faculty of Chemistry, Institute for Biological Chemistry, University of Vienna, Währinger Straße 38, 1090, Vienna, Austria.
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel.
| | - Or Szekely
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Borja Mateos
- Department of Structural and Computational Biology, University of Vienna, Vienna BioCenter 5, 1030, Vienna, Austria
| | - Pavel Kadeřávek
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
- Laboratoire des biomolécules, LBM, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005, Paris, France
| | - Fabien Ferrage
- Laboratoire des biomolécules, LBM, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005, Paris, France
| | - Robert Konrat
- Department of Structural and Computational Biology, University of Vienna, Vienna BioCenter 5, 1030, Vienna, Austria
| | - Roberta Pierattelli
- Magnetic Resonance Center and Department of Chemistry Ugo Schiff, University of Florence, Via L. Sacconi 6, 50019, Sesto Fiorentino, FI, Italy
| | - Isabella C Felli
- Magnetic Resonance Center and Department of Chemistry Ugo Schiff, University of Florence, Via L. Sacconi 6, 50019, Sesto Fiorentino, FI, Italy
| | - Geoffrey Bodenhausen
- Laboratoire des biomolécules, LBM, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005, Paris, France
| | - Dennis Kurzbach
- Faculty of Chemistry, Institute for Biological Chemistry, University of Vienna, Währinger Straße 38, 1090, Vienna, Austria.
- Laboratoire des biomolécules, LBM, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005, Paris, France.
| | - Lucio Frydman
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
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A 300-fold enhancement of imino nucleic acid resonances by hyperpolarized water provides a new window for probing RNA refolding by 1D and 2D NMR. Proc Natl Acad Sci U S A 2020; 117:2449-2455. [PMID: 31949004 DOI: 10.1073/pnas.1916956117] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
NMR sensitivity-enhancement methods involving hyperpolarized water could be of importance for solution-state biophysical investigations. Hyperpolarized water (HyperW) can enhance the 1H NMR signals of exchangeable sites by orders of magnitude over their thermal counterparts, while providing insight into chemical exchange and solvent accessibility at a site-resolved level. As HyperW's enhancements are achieved by exploiting fast solvent exchanges associated with minimal interscan delays, possibilities for the rapid monitoring of chemical reactions and biomolecular (re)folding are opened. HyperW NMR can also accommodate heteronuclear transfers, facilitating the rapid acquisition of 2-dimensional (2D) 15N-1H NMR correlations, and thereby combining an enhanced spectral resolution with speed and sensitivity. This work demonstrates how these qualities can come together for the study of nucleic acids. HyperW injections were used to target the guanine-sensing riboswitch aptamer domain (GSRapt) of the xpt-pbuX operon in Bacillus subtilis Unlike what had been observed in proteins, where residues benefited of HyperW NMR only if/when sufficiently exposed to water, these enhancements applied to every imino resonance throughout the RNA. The >300-fold enhancements observed in the resulting 1H NMR spectra allowed us to monitor in real time the changes that GSRapt undergoes upon binding hypoxanthine, a high-affinity interaction leading to conformational refolding on a ∼1-s timescale at 36 °C. Structural responses could be identified for several nucleotides by 1-dimensional (1D) imino 1H NMR as well as by 2D HyperW NMR spectra acquired upon simultaneous injection of hyperpolarized water and hypoxanthine. The folding landscape revealed by this HyperW strategy for GSRapt, is briefly discussed.
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Nishimura K, Kouno H, Tateishi K, Uesaka T, Ideta K, Kimizuka N, Yanai N. Triplet dynamic nuclear polarization of nanocrystals dispersed in water at room temperature. Phys Chem Chem Phys 2019; 21:16408-16412. [PMID: 31282507 DOI: 10.1039/c9cp03330k] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
While dynamic nuclear polarization using photo-excited triplet electrons (triplet-DNP) can improve the sensitivity of nuclear magnetic resonance at room temperature, it has not been carried out in water. Here, we report the first example of triplet-DNP in water by downsizing the conventional bulk crystals to nanocrystals.
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Affiliation(s)
- Koki Nishimura
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Center for Molecular Systems (CMS), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan.
| | - Hironori Kouno
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Center for Molecular Systems (CMS), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan.
| | - Kenichiro Tateishi
- Cluster for Pioneering Research, Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
| | - Tomohiro Uesaka
- Cluster for Pioneering Research, Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
| | - Keiko Ideta
- Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan
| | - Nobuo Kimizuka
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Center for Molecular Systems (CMS), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan.
| | - Nobuhiro Yanai
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Center for Molecular Systems (CMS), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan. and PRESTO, JST, Honcho 4-1-8, Kawaguchi, Saitama 332-0012, Japan
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