Tautomerism of guanine analogues

0521852 - ÚOCHB 2021 RIV CH eng J - Journal Article
Štoček, Jakub Radek - Dračínský, Martin
Tautomerism of guanine analogues.
Biomolecules. Roč. 10, č. 2 (2020), č. článku 170. E-ISSN 2218-273X
R&D Projects: GA ČR(CZ) GA18-11851S
Institutional support: RVO:61388963
Keywords : nucleic acids * tautomerism * NMR spectroscopy * DFT calculations
OECD category: Physical chemistry
Impact factor: 4.879, year: 2020
Method of publishing: Open access
https://www.mdpi.com/2218-273X/10/2/170

Tautomerism of nucleic acid (NA) bases is a crucial factor for the maintenance and translation of genetic information in organisms. Only canonical tautomers of NA bases can form hydrogen-bonded complexes with their natural counterparts. On the other hand, rare tautomers of nucleobases have been proposed to be involved in processes catalysed by NA enzymes. Isocytosine, which can be considered as a structural fragment of guanine, is known to have two stable tautomers both in solution and solid states. The tautomer equilibrium of isocytosine contrasts with the remarkable stability of the canonical tautomer of guanine. This paper investigates the factors contributing to the stability of the canonical tautomer of guanine by a combination of NMR experiments and theoretical calculations. The electronic effects of substituents on the stability of the rare tautomers of isocytosine and guanine derivatives are studied by density functional theory (DFT) calculations. Selected derivatives are studied by variable-temperature NMR spectroscopy. Rare tautomers can be stabilised in solution by intermolecular hydrogen-bonding interactions with suitable partners. These intermolecular interactions give rise to characteristic signals in proton NMR spectra, which make it possible to undoubtedly confirm the presence of a rare tautomer.
Permanent Link: http://hdl.handle.net/11104/0306406