Publication details

A Study of Cytosine Oligonucleotides by Voltammetric and Spectral Methods



Year of publication 2011
Type Conference abstract
MU Faculty or unit

Faculty of Science

Description For the study of three short homo–deoxyoligonucleotides (homo–ODNs) containing cytosine – dC3 , dC6 and dC9 – we used electrochemical and spectral methods. Using linear sweep voltammetry (LSV) and elimination voltammetry with linear scan (EVLS) the effect of pH and the number of C in the ODN chain on reduction signals in buffered solutions was investigated.1-2 The reduction C peaks, recorded at hanging mercury drop electrode (HMDE) in the potential range from –1.0 V to –1.7 V vs. Ag/AgCl/3 M KCl, are strongly dependent not only on pH but also on the composition of solutions. The measurements were done in phosphate – acetate buffer (0.08 M) with the addition of 0.1M NaCl in pH range from 1.55 to 8.57. The concentration of all ODN was 10 uM. From acidic to alkaline pH scale, three reduction ranges were found. For dC3, dC6 and dC9 we observe on voltammetric curves a shift of the reduction peaks towards more negative potentials with increasing pH and increasing scan rate. It was found that: (a) the peak heights of all ODNs are roughly the same in a range from pH 4 to 6, (b) around pH of 6.5 dC3 provided a double peak which disappeared at higher pHs and one reduction peak was observed, (c) the peak heights of dC6 and dC9 decreased from pH 6.5 to 7.10 resulting in double peaks at higher pH. The different voltammetric behavior of ODNs was confirmed by circular dichroism (CD) spectroscopy, which reveals that the structure of dC6 and dC9 undergoes conformational changes under alkaline conditions, whereas the structure dC3 remainst unchanged. The possible explanation consists in the formation of an i-motif where four dC3 molecules form a very stable associate. The stability of ODNs will be the subject of our future investigation. The occurrence of this unusually stable i-motif is interesting because ODNs as important components of nucleic acids can play a crucial role in the process of genetic information transfer.
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