title: Site-Directed Spin Labeling of RNA by Postsynthetic Modification of 2'-Amino Groups.
abstract: To elucidate mechanisms that govern functions of nucleic acids, it is essential to understand their structure and dynamics. Electron paramagnetic resonance (EPR) spectroscopy is a valuable technique that is routinely used to study those aspects of nucleic acids. A prerequisite for most EPR studies of nucleic acids is incorporation of spin labels at specific sites, known as site-directed spin labeling (SDSL). There are two main strategies for SDSL through formation of covalent bonds, i.e., the phosphoramidite approach and postsynthetic spin-labeling. After describing briefly the advantages and disadvantages of these two strategies, postsynthetic labeling of 2'-amino groups in RNA is delineated. Postsynthetic labeling of 2'-amino groups in RNA using 4-isocyanato-TEMPO has long been established as a useful approach. However, this method has some drawbacks, both with regard to the spin-labeling protocol and the flexibility of the spin label itself. Recently reported isothiocyanate-substituted aromatic isoindoline-derived nitroxides can be used to quantitatively and selectively modify 2'-amino groups in RNA and do not have the drawbacks associated with 4-isocyanato-TEMPO. This chapter provides a detailed description of the postsynthetic spin-labeling methods of 2'-amino groups in RNA with a special focus on using the aromatic isothiocyanate spin labels.
authors.affiliation: Department of Chemistry, Science Institute, University of Iceland, Reykjavik, Iceland.
authors.forename: Subham
authors.initials: S
authors.lastname: Saha
authors.affiliation: Department of Chemistry, Science Institute, University of Iceland, Reykjavik, Iceland.
authors.forename: Anil P
authors.initials: AP
authors.lastname: Jagtap
authors.affiliation: Department of Chemistry, Science Institute, University of Iceland, Reykjavik, Iceland. Electronic address: snorrisi@hi.is.
authors.forename: Snorri Th
authors.initials: ST
authors.lastname: Sigurdsson
mesh_terms: D004247:DNA / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D009589:Nitrogen Oxides / Q000737:chemistry; D009841:Oligonucleotides / Q000737:chemistry; D012313:RNA / Q000737:chemistry*; D013113:Spin Labels
chemical_list: D009589:Nitrogen Oxides; D009841:Oligonucleotides; D013113:Spin Labels; D012313:RNA; D004247:DNA; C039900:nitroxyl
keywords: 2′-Amino RNA; 4-Isocyanato-TEMPO; Aminoxyl radical; EPR; ESR; Isoindoline; Isothiocyanate; Nitroxide; SDSL; Spin labeling