Protonation of Nucleobases in Single- and Double-Stranded DNA.

Autor: González-Olvera JC; Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Instituto Politécnico Nacional, Querétaro, Querétaro, 76090, Mexico.; Universidad Politécnica de Santa Rosa Jáuregui, Santa Rosa Jáuregui, Querétaro, 76220, Mexico., Durec M; CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 753/5, 62500, Brno, Czech Republic., Marek R; CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 753/5, 62500, Brno, Czech Republic., Fiala R; CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 753/5, 62500, Brno, Czech Republic., Morales-García MDRJ; Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Instituto Politécnico Nacional, Querétaro, Querétaro, 76090, Mexico., González-Jasso E; Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Instituto Politécnico Nacional, Querétaro, Querétaro, 76090, Mexico., Pless RC; Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Instituto Politécnico Nacional, Querétaro, Querétaro, 76090, Mexico.
Jazyk: angličtina
Zdroj: Chembiochem : a European journal of chemical biology [Chembiochem] 2018 Oct 04; Vol. 19 (19), pp. 2088-2098. Date of Electronic Publication: 2018 Aug 24.
DOI: 10.1002/cbic.201800310
Abstrakt: Single-stranded model oligodeoxyribonucleotides, each containing a single protonatable base-cytosine, adenine, guanine, or 5-methylcytosine-centrally located in a background of non-protonatable thymine residues, were acid-titrated in aqueous solution, with UV monitoring. The basicity of the central base was shown to depend on the type of the central base and its nearest neighbours and to rise with increasing oligonucleotide length and decreasing ionic strength of the solution. More complex model oligonucleotides, each containing a centrally located 5-methylcytosine base, were comparatively evaluated in single-stranded and double-stranded form, by UV spectroscopy and high-field NMR. The N 3 protonation of the 5-methylcytosine moiety in the double-stranded case occurred at much lower pH, at which the duplex was already experiencing general dissociation, than in the single-stranded case. The central guanine:5-methylcytosine base pair remained intact up to this point, possibly due to an unusual alternative protonation on O 2 of the 5-methylcytosine moiety, already taking place at neutral or weakly basic pH, as indicated by UV spectroscopy, thus suggesting that 5-methylcytosine sites in double-stranded DNA might be protonated to a significant extent under physiological conditions.
(© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)
Databáze: MEDLINE
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