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Substantial difference between temperature dependencies of dsDNA predenaturation process obtained by voltammetry and
Ewelina Zabost1, Anna Maria Nowicka, Mikolaj Donten
1Department of Chemistry, University of Warsaw, ul. Pasteura 1, 02-093 Warsaw, Poland.
Physical Chemistry Chemical Physics : PCCP
|May 8, 2010
Summary
Voltammetry reveals subtle DNA conformational changes before denaturation, offering a more sensitive method than spectroscopy for studying these early events and the impact of intercalators.
Area of Science:
- Electrochemistry
- Biophysical Chemistry
- Molecular Biology
Background:
- Double-stranded DNA (dsDNA) denaturation is typically studied via absorbance changes (melting point).
- Conformational changes preceding denaturation are not fully understood.
- Electrooxidation of DNA bases offers a potential probe for these changes.
Purpose of the Study:
- To investigate the electrooxidation of dsDNA across a wide temperature range.
- To compare voltammetric findings with UV-Vis and Circular Dichroism (CD) spectroscopies.
- To assess the influence of intercalators on dsDNA denaturation.
Main Methods:
- Cyclic and square wave voltammetries.
- UV-Vis spectroscopy.
- Circular Dichroism (CD) spectroscopy.
- Temperature-dependent studies.
Main Results:
- Voltammetric peaks, linked to guanine and adenine electrooxidation, increased ~20°C below the melting point, indicating early conformational changes.
- These changes suggest increased exposition of guanine and adenine bases preceding denaturation.
- Spectroscopic methods confirmed increased dsDNA stability and reduced base exposition upon addition of an intercalator.
Conclusions:
- Voltammetric methods are more sensitive than UV-Vis and CD for detecting early dsDNA conformational changes.
- Early conformational alterations in G-C and A-T pairs likely cause the observed voltammetric signal increase.
- Intercalators stabilize dsDNA structure, reducing base accessibility for electrooxidation.
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