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DNA Heptamers with Different Central Trinucleotide Sequences Studied by Electrochemical and Spectral Methods

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Year of publication 2015
Type Conference abstract
MU Faculty or unit

Faculty of Science

Description Monitoring the relationship between a structure and the corresponding electrochemical response is very important not only from the aspect of the knowledge of dynamic structural changes to the charged interface (electrode surface, membrane, surface of the gel), but also in terms of proper evaluation of the electrochemical signals for potential biosensors. This relationship was studied for the case of short DNA fragments, the heptamer d(GCGaagc) with its analogs carrying different trinucleotide sequences in the center of the molecule (XXX = AAA, CCC, GGG or TTT) and hexamers of d(GCGAGC) type with different dinucleotide sequences. All fragments were investigated by spectral and electrochemical methods (cyclic and linear sweep voltammetry polyacrylamide gel electrophoresis). For deeper understanding of DNA heptamers and hexamers behavior on the electrode surface (mercury and carbon) the elimination voltammetric procedure (EVP) for reduction and oxidation responses was used. The EVP indicated strong adsorption of reduced form of guanine on a mercury electrode (readable peak-counterpeak signal). Our results showed that (i) the central triplet GAA or AAA dramatically stabilizes DNA heptamers, (ii) a stem-loop configuration is not supported by CCC or TTT sequences, instead, these heptamers adopt bimolecular duplex forms, and finally (iii) in the case of GGG sequence a very stable supramolecular G-quadruplex is formed. Int he enxt experiments, we compared DNA and RNA fragments. DNA heptamers and hexamers provided double oxidation peaks (GI and GII) while RNA analogs provide only a single G peak. Based on this fact, DNA or RNA fragments can be quickly and inexpensively distinguished.
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