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Updated: Jun 6, 2026

Extremely Rapid and Specific Metabolic Labelling of RNA In Vivo with 4-Thiouracil (Ers4tU)
Published on: August 22, 2019
Tautomerism in 4-hydroxypyrimidine, S-methyl-2-thiouracil, and 2-thiouracil
Barbara M Giuliano1, Vitaliy Feyer, Kevin C Prince
1Departamento de Química da Universidade de Coimbra, 3004-535 Coimbra, Portugal.
Abstract:
The keto-enol tautomerism of 4-hydroxypyrimidine and of the related molecules S-methyl-2-thiouracil and 2-thiouracil has been investigated using synchrotron-based techniques. The populations of the constituent tautomers and thermodynamic parameters have been obtained by analysis of core-level photoemission spectra. The effect of substituents on the stability of tautomers has been revealed. Attaching additional OH (or SH) groups to the aromatic ring stabilizes the dioxo (or oxo-thione) forms. However, substitution of hydrogen in position 2 by an S-CH(3) group (that is, in going from 4-hydroxypyrimidine to S-methyl-2-thiouracil) does not significantly affect the tautomeric equilibrium.
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