title: The "Speedy" Synthesis of Atom-Specific (15)N Imino/Amido-Labeled RNA.
abstract: Although numerous reports on the synthesis of atom-specific (15)N-labeled nucleosides exist, fast and facile access to the corresponding phosphoramidites for RNA solid-phase synthesis is still lacking. This situation represents a severe bottleneck for NMR spectroscopic investigations on functional RNAs. Here, we present optimized procedures to speed up the synthesis of (15)N(1) adenosine and (15)N(1) guanosine amidites, which are the much needed counterparts of the more straightforward-to-achieve (15)N(3) uridine and (15)N(3) cytidine amidites in order to tap full potential of (1)H/(15)N/(15)N-COSY experiments for directly monitoring individual Watson-Crick base pairs in RNA. Demonstrated for two preQ1 riboswitch systems, we exemplify a versatile concept for individual base-pair labeling in the analysis of conformationally flexible RNAs when competing structures and conformational dynamics are encountered.
authors.affiliation: Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck (Austria).
authors.forename: Sandro
authors.initials: S
authors.lastname: Neuner
authors.affiliation: Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck (Austria).
authors.forename: Tobias
authors.initials: T
authors.lastname: Santner
authors.affiliation: Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck (Austria).
authors.forename: Christoph
authors.initials: C
authors.lastname: Kreutz
authors.affiliation: Institute of Organic Chemistry, Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck (Austria).
authors.forename: Ronald
authors.initials: R
authors.lastname: Micura
mesh_terms: D000241:Adenosine / Q000138:chemical synthesis* / Q000737:chemistry; D020029:Base Pairing; D003562:Cytidine / Q000737:chemistry*; D006151:Guanosine / Q000138:chemical synthesis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D009690:Nucleic Acid Conformation; D009705:Nucleosides / Q000737:chemistry*; D063088:Phosphoramides / Q000138:chemical synthesis* / Q000737:chemistry*; D012313:RNA / Q000737:chemistry*; D060327:Solid-Phase Synthesis Techniques; D014529:Uridine / Q000737:chemistry*
chemical_list: D009705:Nucleosides; D063088:Phosphoramides; D006151:Guanosine; D003562:Cytidine; D012313:RNA; D000241:Adenosine; D014529:Uridine
keywords: NMR spectroscopy; nucleosides; oligonucleotides; phosphoramidites