Electrochemical oxidation-reduction paths for pyrimidine, cytosine, purine and adenineCorrelation and application

Abstract

In order to evaluate the striking discrepancy between the experimental ease of polarographic reduction of adenine and cytosine, and that predicted by molecular orbital calculation, the electrochemical oxidation-reduction behaviour of pyrimidine, cytosine, purine, adenine and related compounds was investigated at both mercury and graphite electrodes. Information was obtained on the specific adsorption of reactant and product species on the electrode, the reversibility of the energy-controlling electron-transfer step, and accompanying chemical reactions. Triangular sweep voltammetry, a.c. and d.c. polarography, and electrocapillary data, in particular, were utilized. The first three techniques were critically examined for their potential analytical utility. The results were compared with previously obtained electrochemical data and the sequence of electron-transfer and various non-electron transfer steps was more firmly established. It became clear that in order validly to correlate quantum mechanically calculated data for the energy required to add or remove an electron to or from the outermost electron level of each molecule (in the gas phase), with electrochemical redox potentials (in solution), the effects of adsorption, electron-transfer reversibility and solvation energy must be considered.

Voltammetric determination of all DNA nucleotides

“…Thus, the numbers of protons and electrons involved in the oxidation of both purines were equal over the entire pH range [19].…”

Electrochemical methods for determination of thymine in medical pipefish samples based on HPMαFP/Ppy/GCE-modified electrode

“…The electrochemical studies have been undertaken concerning their redox behavior at mercury electrode, yet thymine was reported to show no polargraphic reduction wave. In addition, the pyrimidine forms sparingly soluble compounds with Hg(II) at the surface of mercury electrode, which allows their determination by cathodic stripping voltammeters [3][4][5][6]. Due to low signal-to-noise ratio and their extreme positive oxidation potentials, thymine and cytosine have been assumed to exhibit no electrochemical activity at graphite electrodes [7,8] or carbon-based electrodes in general [9,10].…”

Studies on the adsorption and the association of cytidine sulphate at the dropping mercury electrode with phase-sensitive ac-polarography

“…The adsorption properties of some bases, nucleosides and mononucleotides, present in the nucleic acid have been studied at the mercury electrode (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17). Previous investigations have been made by Vetterl and co-workers (5-9) on pyrimidine and purine bases and nucleotides and by Elving and co-workers (10-13) on adenine and cytosine monoand oligonucleotides using measurement of the changes of the double layer capacity with the impedance bridge or by means of total ac-polarography.…”