Conformatzonal Properties of a Novel Modified Nucleoside, 5-Formylcytidine, Found at the First Position of the Anticodon of Bovine Mitochondrial tRNAMet

Abstract

Abstract Conformational properties of a novel modified nucleoside, 5-formylcytidine (f5C), which is found at the first position of the anticodon of bovine mitochondrial tRNAMet, were analyzed by 1H-NMR spectroscopy. f5C has a normal amino tautomeric form at position 4 of the base moiety. The results indicate the presence of an intramolecular hydrogen bond between the carbony1 of the 5-formyl group and the 4-amino function. f5C was found to exhibit the C3′-endo conformation exclusively and the enthalpy difference (ΔH) between the C2′-endo and C3′- endo forms was found to be 1.56 ± 0.13 kcal/mol, indicating f5C to be one of the most conformationally rigid nucleosides yet analyzed. The conformational rigidity of f5C may contribute to regulation of codon recognition by tRNAMet.