Synthesis of atom-specific nucleobase and ribose labeled uridine phosphoramidite for NMR analysis of large RNAs

Abstract

We describe the hybrid enzymatic and chemical synthesis of a 2′-O-cyanoethoxymethyl (CEM) [1′,6-13C2, 5-2H]-uridine phosphoramidite (amidite). This is the first report of an atom-specific nucleobase and ribose labeled CEM amidite. Importantly, the CEM 2′-OH protecting group permits the efficient solid-phase synthesis of large (>\u200960 nucleotides) RNAs with good yield and purity. Therefore, our isotope-labeled amidite can be used to make large, position-specifically labeled RNAs for NMR analysis without complications from resonance overlap and scalar and dipolar couplings.