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Taiwo KM, Olenginski LT, Nußbaumer F, Nam H, Hilber S, Kreutz C, Dayie TK. Synthesis of [7- 15N]-GTPs for RNA structure and dynamics by NMR spectroscopy. MONATSHEFTE FUR CHEMIE 2022; 153:293-299. [PMID: 35400760 PMCID: PMC8948113 DOI: 10.1007/s00706-022-02892-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 01/11/2022] [Indexed: 12/23/2022]
Abstract
Several isotope-labeling strategies have been developed for the study of RNA by nuclear magnetic resonance (NMR) spectroscopy. Here, we report a combined chemical and enzymatic synthesis of [7-15N]-guanosine-5'-triphosphates for incorporation into RNA via T7 RNA polymerase-based in vitro transcription. We showcase the utility of these labels to probe both structure and dynamics in two biologically important RNAs. Graphical abstract Supplementary Information The online version contains supplementary material available at 10.1007/s00706-022-02892-1.
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Affiliation(s)
- Kehinde M. Taiwo
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, MD 20742 USA
| | - Lukasz T. Olenginski
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, MD 20742 USA
| | - Felix Nußbaumer
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Hyeyeon Nam
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, MD 20742 USA
- Present Address: Center for Cancer Research, National Cancer Institute, Frederick, MD 21702 USA
| | - Stefan Hilber
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - T. Kwaku Dayie
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, MD 20742 USA
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2
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Nelissen FHT, Tessari M, Wijmenga SS, Heus HA. Stable isotope labeling methods for DNA. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2016; 96:89-108. [PMID: 27573183 DOI: 10.1016/j.pnmrs.2016.06.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 06/02/2016] [Accepted: 06/02/2016] [Indexed: 06/06/2023]
Abstract
NMR is a powerful method for studying proteins and nucleic acids in solution. The study of nucleic acids by NMR is far more challenging than for proteins, which is mainly due to the limited number of building blocks and unfavorable spectral properties. For NMR studies of DNA molecules, (site specific) isotope enrichment is required to facilitate specific NMR experiments and applications. Here, we provide a comprehensive review of isotope-labeling strategies for obtaining stable isotope labeled DNA as well as specifically stable isotope labeled building blocks required for enzymatic DNA synthesis.
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Affiliation(s)
- Frank H T Nelissen
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands.
| | - Marco Tessari
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands.
| | - Sybren S Wijmenga
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands.
| | - Hans A Heus
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands.
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3
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Alvarado LJ, Longhini AP, LeBlanc RM, Chen B, Kreutz C, Dayie TK. Chemo-enzymatic synthesis of selectively ¹³C/¹⁵N-labeled RNA for NMR structural and dynamics studies. Methods Enzymol 2015; 549:133-62. [PMID: 25432748 DOI: 10.1016/b978-0-12-801122-5.00007-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
RNAs are an important class of cellular regulatory elements, and they are well characterized by X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy in their folded or bound states. However, the apo or unfolded states are more difficult to characterize by either method. Particularly, effective NMR spectroscopy studies of RNAs in the past were hampered by chemical shift overlap of resonances and associated rapid signal loss due to line broadening for RNAs larger than the median size found in the PDB (~25 nt); most functional riboswitches are bigger than this median size. Incorporation of selective site-specific (13)C/(15)N-labeled nucleotides into RNAs promises to overcome this NMR size limitation. Unlike previous isotopic enrichment methods such as phosphoramidite, de novo, uniform-labeling, and selective-biomass approaches, this newer chemical-enzymatic selective method presents a number of advantages for producing labeled nucleotides over these other methods. For example, total chemical synthesis of nucleotides, followed by solid-phase synthesis of RNA using phosphoramidite chemistry, while versatile in incorporating isotope labels into RNA at any desired position, faces problems of low yields (<10%) that drop precipitously for oligonucleotides larger than 50 nt. The alternative method of de novo pyrimidine biosynthesis of NTPs is also a robust technique, with modest yields of up to 45%, but it comes at the cost of using 16 enzymes, expensive substrates, and difficulty in making some needed labeling patterns such as selective labeling of the ribose C1' and C5' and the pyrimidine nucleobase C2, C4, C5, or C6. Biomass-produced, uniformly or selectively labeled NTPs offer a third method, but suffer from low overall yield per labeled input metabolite and isotopic scrambling with only modest suppression of (13)C-(13)C couplings. In contrast to these four methods, our current chemo-enzymatic approach overcomes most of these shortcomings and allows for the synthesis of gram quantities of nucleotides with >80% yields while using a limited number of enzymes, six at most. The unavailability of selectively labeled ribose and base precursors had prevented the effective use of this versatile method until now. Recently, we combined an improved organic synthetic approach that selectively places (13)C/(15)N labels in the pyrimidine nucleobase (either (15)N1, (15)N3, (13)C2, (13)C4, (13)C5, or (13)C6 or any combination) with a very efficient enzymatic method to couple ribose with uracil to produce previously unattainable labeling patterns (Alvarado et al., 2014). Herein we provide detailed steps of both our chemo-enzymatic synthesis of custom nucleotides and their incorporation into RNAs with sizes ranging from 29 to 155 nt and showcase the dramatic improvement in spectral quality of reduced crowding and narrow linewidths. Applications of this selective labeling technology should prove valuable in overcoming two major obstacles, chemical shift overlap of resonances and associated rapid signal loss due to line broadening, that have impeded studying the structure and dynamics of large RNAs such as full-length riboswitches larger than the ~25 nt median size of RNA NMR structures found in the PDB.
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Affiliation(s)
- Luigi J Alvarado
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure & Organization, University of Maryland, College Park, Maryland, USA
| | - Andrew P Longhini
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure & Organization, University of Maryland, College Park, Maryland, USA
| | - Regan M LeBlanc
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure & Organization, University of Maryland, College Park, Maryland, USA
| | - Bin Chen
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure & Organization, University of Maryland, College Park, Maryland, USA
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences (CMBI), University of Innsbruck, Innrain, Innsbruck, Austria
| | - T Kwaku Dayie
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure & Organization, University of Maryland, College Park, Maryland, USA.
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4
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Weissman BP, Li NS, York D, Harris M, Piccirilli JA. Heavy atom labeled nucleotides for measurement of kinetic isotope effects. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:1737-45. [PMID: 25828952 DOI: 10.1016/j.bbapap.2015.03.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 03/06/2015] [Accepted: 03/18/2015] [Indexed: 02/01/2023]
Abstract
Experimental analysis of kinetic isotope effects represents an extremely powerful approach for gaining information about the transition state structure of complex reactions not available through other methodologies. The implementation of this approach to the study of nucleic acid chemistry requires the synthesis of nucleobases and nucleotides enriched for heavy isotopes at specific positions. In this review, we highlight current approaches to the synthesis of nucleic acids enriched site specifically for heavy oxygen and nitrogen and their application in heavy atom isotope effect studies. This article is part of a special issue titled: Enzyme Transition States from Theory and Experiment.
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Affiliation(s)
| | - Nan-Sheng Li
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
| | - Darrin York
- Center for Integrative Proteomics Research, Biology at the Interface with the Mathematical and Physical Sciences (BioMaPS) Institute for Quantitative Biology, The State University of New Jersey, Piscataway, NJ, USA; Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Michael Harris
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Joseph A Piccirilli
- Department of Chemistry, University of Chicago, Chicago, IL, USA; Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA.
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5
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Alvarado LJ, LeBlanc RM, Longhini AP, Keane SC, Jain N, Yildiz ZF, Tolbert BS, D'Souza VM, Summers MF, Kreutz C, Dayie TK. Regio-selective chemical-enzymatic synthesis of pyrimidine nucleotides facilitates RNA structure and dynamics studies. Chembiochem 2014; 15:1573-7. [PMID: 24954297 DOI: 10.1002/cbic.201402130] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Indexed: 12/16/2022]
Abstract
Isotope labeling has revolutionized NMR studies of small nucleic acids, but to extend this technology to larger RNAs, site-specific labeling tools to expedite NMR structural and dynamics studies are required. Using enzymes from the pentose phosphate pathway, we coupled chemically synthesized uracil nucleobase with specifically (13) C-labeled ribose to synthesize both UTP and CTP in nearly quantitative yields. This chemoenzymatic method affords a cost-effective preparation of labels that are unattainable by current methods. The methodology generates versatile (13) C and (15) N labeling patterns which, when employed with relaxation-optimized NMR spectroscopy, effectively mitigate problems of rapid relaxation that result in low resolution and sensitivity. The methodology is demonstrated with RNAs of various sizes, complexity, and function: the exon splicing silencer 3 (27 nt), iron responsive element (29 nt), Pro-tRNA (76 nt), and HIV-1 core encapsidation signal (155 nt).
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Affiliation(s)
- Luigi J Alvarado
- Center for Biomolecular Structure and Organization, Department of Chemistry and Biochemistry, University of Maryland, 1115 Biomolecular Sciences Building, College Park, MD 20782 (USA)
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6
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Thakur CS, Dayie TK. Asymmetry of 13C labeled 3-pyruvate affords improved site specific labeling of RNA for NMR spectroscopy. JOURNAL OF BIOMOLECULAR NMR 2012; 52:65-77. [PMID: 22089526 PMCID: PMC3266500 DOI: 10.1007/s10858-011-9582-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2011] [Accepted: 10/10/2011] [Indexed: 05/07/2023]
Abstract
Selective isotopic labeling provides an unparalleled window within which to study the structure and dynamics of RNAs by high resolution NMR spectroscopy. Unlike commonly used carbon sources, the asymmetry of (13)C-labeled pyruvate provides selective labeling in both the ribose and base moieties of nucleotides using Escherichia coli variants, that until now were not feasible. Here we show that an E. coli mutant strain that lacks succinate and malate dehydrogenases (DL323) and grown on [3-(13)C]-pyruvate affords ribonucleotides with site specific labeling at C5' (~95%) and C1' (~42%) and minimal enrichment elsewhere in the ribose ring. Enrichment is also achieved at purine C2 and C8 (~95%) and pyrimidine C5 (~100%) positions with minimal labeling at pyrimidine C6 and purine C5 positions. These labeling patterns contrast with those obtained with DL323 E. coli grown on [1, 3-(13)C]-glycerol for which the ribose ring is labeled in all but the C4' carbon position, leading to multiplet splitting of the C1', C2' and C3' carbon atoms. The usefulness of these labeling patterns is demonstrated with a 27-nt RNA fragment derived from the 30S ribosomal subunit. Removal of the strong magnetic coupling within the ribose and base leads to increased sensitivity, substantial simplification of NMR spectra, and more precise and accurate dynamic parameters derived from NMR relaxation measurements. Thus these new labels offer valuable probes for characterizing the structure and dynamics of RNA that were previously limited by the constraint of uniformly labeled nucleotides.
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Affiliation(s)
- Chandar S. Thakur
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, 1115 Biomolecular Sciences Bldg (#296), College Park, MD 20742-3360 USA
| | - T. Kwaku Dayie
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, 1115 Biomolecular Sciences Bldg (#296), College Park, MD 20742-3360 USA
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7
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Fürtig B, Buck J, Richter C, Schwalbe H. Functional dynamics of RNA ribozymes studied by NMR spectroscopy. Methods Mol Biol 2012; 848:185-199. [PMID: 22315070 DOI: 10.1007/978-1-61779-545-9_12] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Catalytic RNA motifs (ribozymes) are involved in various cellular processes. Although functional cleavage of the RNA phosphodiester backbone for self-cleaving ribozymes strongly differs with respect to sequence specificity, the structural context, and the underlying mechanism, these ribozyme motifs constitute evolved RNA molecules that carry out identical chemical functionality. Therefore, they represent ideal systems for detailed studies of the underlying structure-function relationship, illustrating the diversity of RNA's functional role in biology. Nuclear magnetic resonance (NMR) spectroscopic methods in solution allow investigation of structure and dynamics of functional RNA motifs at atomic resolution. In addition, characterization of RNA conformational transitions initiated either through addition of specific cofactors, as e.g. ions or small molecules, or by photo-chemical triggering of essential RNA functional groups provides insights into the reaction mechanism. Here, we discuss applications of static and time-resolved NMR spectroscopy connected with the design of suitable NMR probes that have been applied to characterize global and local RNA functional dynamics together with cleavage-induced conformational transitions of two RNA ribozyme motifs: a minimal hammerhead ribozyme and an adenine-dependent hairpin ribozyme.
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Affiliation(s)
- Boris Fürtig
- Institute of Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
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8
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Thakur CS, Dayie TK. Asymmetry of (13)C labeled 3-pyruvate affords improved site specific labeling of RNA for NMR spectroscopy. JOURNAL OF BIOMOLECULAR NMR 2011; 51:505-17. [PMID: 22038649 PMCID: PMC3222825 DOI: 10.1007/s10858-011-9581-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Accepted: 10/11/2011] [Indexed: 05/15/2023]
Abstract
Selective isotopic labeling provides an unparalleled window within which to study the structure and dynamics of RNAs by high resolution NMR spectroscopy. Unlike commonly used carbon sources, the asymmetry of (13)C-labeled pyruvate provides selective labeling in both the ribose and base moieties of nucleotides using E. coli variants, that until now were not feasible. Here we show that an E. coli mutant strain that lacks succinate and malate dehydrogenases (DL323) and grown on [3-(13)C]-pyruvate affords ribonucleotides with site specific labeling at C5' (~95%) and C1' (~42%) and minimal enrichment elsewhere in the ribose ring. Enrichment is also achieved at purine C2 and C8 (~95%) and pyrimidine C5 (~100%) positions with minimal labeling at pyrimidine C6 and purine C5 positions. These labeling patterns contrast with those obtained with DL323 E. coli grown on [1, 3-(13)C]-glycerol for which the ribose ring is labeled in all but the C4' carbon position, leading to multiplet splitting of the C1', C2' and C3' carbon atoms. The usefulness of these labeling patterns is demonstrated with a 27-nt RNA fragment derived from the 30S ribosomal subunit. Removal of the strong magnetic coupling within the ribose and base leads to increased sensitivity, substantial simplification of NMR spectra, and more precise and accurate dynamic parameters derived from NMR relaxation measurements. Thus these new labels offer valuable probes for characterizing the structure and dynamics of RNA that were previously limited by the constraint of uniformly labeled nucleotides.
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Affiliation(s)
- Chandar S. Thakur
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure & Organization, University of Maryland, 1115 Biomolecular Sciences Bldg (#296), College Park, MD 20742-3360 USA
| | - T. Kwaku Dayie
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure & Organization, University of Maryland, 1115 Biomolecular Sciences Bldg (#296), College Park, MD 20742-3360 USA
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9
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Dayie TK, Thakur CS. Site-specific labeling of nucleotides for making RNA for high resolution NMR studies using an E. coli strain disabled in the oxidative pentose phosphate pathway. JOURNAL OF BIOMOLECULAR NMR 2010; 47:19-31. [PMID: 20309608 PMCID: PMC2859161 DOI: 10.1007/s10858-010-9405-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Accepted: 02/26/2010] [Indexed: 05/22/2023]
Abstract
Escherichia coli (E. coli) is a versatile organism for making nucleotides labeled with stable isotopes ((13)C, (15)N, and/or (2)H) for structural and molecular dynamics characterizations. Growth of a mutant E. coli strain deficient in the pentose phosphate pathway enzyme glucose-6-phosphate dehydrogenase (K10-1516) on 2-(13)C-glycerol and (15)N-ammonium sulfate in Studier minimal medium enables labeling at sites useful for NMR spectroscopy. However, (13)C-sodium formate combined with (13)C-2-glycerol in the growth media adds labels to new positions. In the absence of labeled formate, both C5 and C6 positions of the pyrimidine rings are labeled with minimal multiplet splitting due to (1)J(C5C6) scalar coupling. However, the C2/C8 sites within purine rings and the C1'/C3'/C5' positions within the ribose rings have reduced labeling. Addition of (13)C-labeled formate leads to increased labeling at the base C2/C8 and the ribose C1'/C3'/C5' positions; these new specific labels result in two- to three-fold increase in the number of resolved resonances. This use of formate and (15)N-ammonium sulfate promises to extend further the utility of these alternate site specific labels to make labeled RNA for downstream biophysical applications such as structural, dynamics and functional studies of interesting biologically relevant RNAs.
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Affiliation(s)
- T Kwaku Dayie
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, 1115 Biomolecular Sciences Bldg (#296), College Park, MD 20742-3360, USA.
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10
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Abstract
This review describes the various manifestations of the pyrimidine system (alkylated, glycosylated, benzo-annelated.). These comprise pyrimidine nucleosides as well as alkaloids and antibiotics--some of them have been discovered and isolated from natural sources already long time ago, others have been reported very recently. A short overview on pyrimidine syntheses (prebiotic synthesis, biosynthesis, and metabolism) is given. The biological activities of most of the pyrimidine analogs are briefly described, and, in some cases, syntheses are formulated.
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Affiliation(s)
- Irene M Lagoja
- Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven.
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11
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Kamaike K, Kayama Y, Mitsuhisa I, Etsuko K. Efficient synthesis of [2-15N]guanosine and 2'-deoxy[2'-15N]guanosine derivatives using N-(tert-butyldimethylsilyl)[15N]phthalimide as a 15N-labeling reagent. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2006; 25:29-35. [PMID: 16440983 DOI: 10.1080/15257770500377771] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Nucleophilic aromatic substitution of 9-(2,3,5-tri-O-acetyl-beta-D-ribofuranosyl)-6-chloro-2-fluoro-9H-purine with N-(tert-butyldimethylsilyl) [15N]phthalimide in the presence of a catalytic amount of CsF at room temperature in DMF efficiently afforded the 6-chloro-2-[15N]phthalimidopurine derivative, which was subsequently converted to the [2-15N]guanosine derivative. The 2'-deoxy[2'-15N]guanosine derivative was also efficiently synthesized through a similar procedure.
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Affiliation(s)
- Kazuo Kamaike
- School of Pharmarcy, Tokyo University of Pharmarcy and Life Sciences, Hachioji, Tokyo, Japan.
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12
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Terrazas M, Ariza X, Vilarrasa J. Advantages of the Ns group in the reactions of N1-SO2R inosines with benzylamine and with 15NH3. Tetrahedron Lett 2005. [DOI: 10.1016/j.tetlet.2005.05.137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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13
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Sako M, Kawada H. A New and Efficient Synthetic Method for 15N3-Labeled Cytosine Nucleosides: Dimroth Rearrangement of Cytidine N3-Oxides. J Org Chem 2004; 69:8148-50. [PMID: 15527310 DOI: 10.1021/jo0486241] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The treatment of (15)N(4)-labeled cytidine N(3)-oxide and (15)N(4)-labeled 2'-deoxycytidine N(3)-oxide, prepared from the appropriate unprotected uridines in three reaction steps, with benzyl bromide in the presence of excess lithium methoxide allowed the smooth occurrence of their Dimroth rearrangement even under mild conditions leading to the corresponding (15)N(3)-labeled uridine 4-O-benzyloximes which can easily undergo the reductive N-O bond cleavage to give the desirable (15)N(3)-labeled cytosine nucleosides in high total yields.
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Affiliation(s)
- Magoichi Sako
- Gifu Pharmaceutical University, 5-6-1, Mitahora-higashi, Gifu 502-8585, Japan.
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14
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Saito Y, Zevaco TA, Agrofoglio LA. Chemical synthesis of 13C labeled anti-HIV nucleosides as mass-internal standards. Tetrahedron 2002. [DOI: 10.1016/s0040-4020(02)01246-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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