Thiolation of uridine carbon-2 restricts the motional dynamics of the transfer RNA wobble position nucleoside

Thiolation of transfer RNA wobble position uridines produces a preferred conformation of the nucleoside in solution at ambient temperature that is of biological significance to codon recognition [Sierzputowska-Gracz, H.; Sochacka, E.; Malkiewicz, A.; Kuo, K.; Gehrke, C.; Agris, P. F. J. Am. Chem. Soc. 1987, 109, 7171-7177]. We investigated and compared, by proton nuclear magnetic resonance (NMR) spectroscopy, the thermodynamic stability of the conformations of 2-thiouridine and five biologically important 5-position derivatives and the six analogous uridines