Oxidation potentials of guanine, guanosine and guanosine-5 '-monophosphate: Theory and experiment

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61388955%3A_____%2F19%3A00508035" target="_blank" >RIV/61388955:_____/19:00508035 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216224:14310/19:00111052

Výsledek na webu

<a href="http://hdl.handle.net/11104/0298989" target="_blank" >http://hdl.handle.net/11104/0298989</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.electacta.2019.06.052" target="_blank" >10.1016/j.electacta.2019.06.052</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Oxidation potentials of guanine, guanosine and guanosine-5 '-monophosphate: Theory and experiment

Popis výsledku v původním jazyce

Guanine, having lower one-electron oxidation potential than other nucleobases, is of relevance to oxidative degradation of nucleic acids in mutagenesis, carcinogenesis, and aging. Here we compare oxidation potentials of guanine (G), guanosine (Guo), deoxyguanosine (dGuo), guanosine-5'-monophosphate (GMP) and 2'-deoxyguanosine-5'-monophosphate (dGMP) obtained by theoretical and experimental methods. Structures of G species were optimized and the identities of minima were verified by vibration frequency calculations. Redox equilibria were modelled in terms of corresponding thermochemical cycles. The changes in free energy were calculated at DFT level using the two different functionals: (i) general purpose B3LYP functional, and (ii) more specific omega B97X-D functional (both with 6-31 + G(d) basis set). Experimental oxidation potentials of all G analogues were measured voltam-metrically on a polymer pencil graphite electrode (pPeGE) providing the best results from all carbon electrodes used (glassy carbon electrode, basal and edge plane pyrolytic graphite electrodes). The oxidation process is strongly dependent on the pH value and with increasing pH a linear shift of G oxidation peaks (E-pa) towards negative potentials is observed. The theoretically and experimentally obtained oxidation potentials were compared for the pH 5. Anodic peak potentials increase in the order G << dGMP <= GMP < dGuo <= Guo and correlate with the calculated thermodynamic redox potentials as well as with NBO charges in purine moiety. The oxidation of deoxy analogues was predicted theoretically to occur at lower potentials than that of corresponding parent compounds and this fact was experimentally verified. The assumption that due to negatively charged phosphate group of GMP or dGMP their oxidation potentials could be observed at lower positive potential has not been confirmed and the significant difference (more than 200 mV) between the oxidation potentials of G nucleobase and its nucleosides and nucleotides is discussed. Moreover, conformity of theoretical and experimental data for radicals (cation, neutral) indicates that while the deprotonation process of G differs from its analogues, the oxidation process of all species takes place on imidazole ring. (C) 2019 Published by Elsevier Ltd.

Název v anglickém jazyce

Oxidation potentials of guanine, guanosine and guanosine-5 '-monophosphate: Theory and experiment

Popis výsledku anglicky

Guanine, having lower one-electron oxidation potential than other nucleobases, is of relevance to oxidative degradation of nucleic acids in mutagenesis, carcinogenesis, and aging. Here we compare oxidation potentials of guanine (G), guanosine (Guo), deoxyguanosine (dGuo), guanosine-5'-monophosphate (GMP) and 2'-deoxyguanosine-5'-monophosphate (dGMP) obtained by theoretical and experimental methods. Structures of G species were optimized and the identities of minima were verified by vibration frequency calculations. Redox equilibria were modelled in terms of corresponding thermochemical cycles. The changes in free energy were calculated at DFT level using the two different functionals: (i) general purpose B3LYP functional, and (ii) more specific omega B97X-D functional (both with 6-31 + G(d) basis set). Experimental oxidation potentials of all G analogues were measured voltam-metrically on a polymer pencil graphite electrode (pPeGE) providing the best results from all carbon electrodes used (glassy carbon electrode, basal and edge plane pyrolytic graphite electrodes). The oxidation process is strongly dependent on the pH value and with increasing pH a linear shift of G oxidation peaks (E-pa) towards negative potentials is observed. The theoretically and experimentally obtained oxidation potentials were compared for the pH 5. Anodic peak potentials increase in the order G << dGMP <= GMP < dGuo <= Guo and correlate with the calculated thermodynamic redox potentials as well as with NBO charges in purine moiety. The oxidation of deoxy analogues was predicted theoretically to occur at lower potentials than that of corresponding parent compounds and this fact was experimentally verified. The assumption that due to negatively charged phosphate group of GMP or dGMP their oxidation potentials could be observed at lower positive potential has not been confirmed and the significant difference (more than 200 mV) between the oxidation potentials of G nucleobase and its nucleosides and nucleotides is discussed. Moreover, conformity of theoretical and experimental data for radicals (cation, neutral) indicates that while the deprotonation process of G differs from its analogues, the oxidation process of all species takes place on imidazole ring. (C) 2019 Published by Elsevier Ltd.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10403 - Physical chemistry

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2019

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Electrochimica acta

ISSN

0013-4686

e-ISSN

—

Svazek periodika

318

Číslo periodika v rámci svazku

SEP 2019

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

12

Strana od-do

108-119

Kód UT WoS článku

000478969600013

EID výsledku v databázi Scopus

2-s2.0-85067351109