The association constant of 5',8-cyclo-2'-deoxyguanosine with cytidine.

Amedeo Capobianco,Tonino Caruso,Annalisa Masi,Chryssostomos Chatgilialoglu,Michael A Terzidis,Andrea Peluso,Sabato Fusco

doi:10.3389/fchem.2015.00022

Abstract

The association of 5′,8-cyclo-2′-deoxyguanosine (cdG), a DNA tandem lesion, with its complementary base cytosine has been studied by voltammetry and NMR in chloroform, using properly silylated derivatives of the two nucleobases for increasing their solubilities. Both voltammetric data and NMR titrations indicated that the Watson-Crick complex of cytidine with cdG is weaker than that with guanosine, the difference being approximately of one order of magnitude between the two association constants.

Highlights

The level of distortion in DNA double helix is highly evaluated for the recognition and the repair of DNA lesions in cells
The differential pulse voltammogram of a 1.0 mM solution of ScdG’ in chloroform is reported in Figure 1; an irreversible oxidation peak is observed at 0.95 V vs. ferrocenium/ferrocene couple (Fc+/Fc), a potential very close to the one (0.91 V) observed for the oxidation of dG’ (Caruso et al, 2005) indicating that the formation of the C8–C5′ covalent bond does not constitute a severe perturbation of the π system of guanine, as expected
The voltammogram of an equimolar solution of ScdG’ and dC’ (Figure 1, black curve) exhibits two voltammetric signals, one occurring at the same potential observed for solutions containing only 5′,8-cyclo-2′-deoxyguanosine, which can be safely assigned to the fraction of free ScdG’ in solution, the other peaked at 0.77 V

Summary

Introduction

The level of distortion in DNA double helix is highly evaluated for the recognition and the repair of DNA lesions in cells. Among the various lesions that can be produced as consequence of metabolic processes and other external factors (oxidizing agents, drugs, ionizing, and non-ionizing irradiation, etc.) are the 5′,8-cyclo-2′-deoxypurines (cdP) where the base is covalently connected with the sugar with an extra carbon-carbon bond apart from the usual glycosidic bond (Chatgilialoglu et al, 2011). Both cdA and cdG lesions exist as 5′R- and 5′S-diastereomers. Recent studies reported cyclopurine lesions as reliable oxidative stress biomarkers in animal models (Wang et al, 2011; Mitra et al, 2012)

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Results

Conclusion