Abstract
The heat capacity (ΔC P ) effects on the unfolding of a macromolecule play a significant role in the magnitude of their standard thermodynamic profiles; all three thermodynamic parameters (enthalpy, entropy and free energy) are dependent on temperature. The ΔC P of proteins is typically significant and is easily obtained using DSC by taking the difference in the ΔC P values of the pre- and post-transitional baselines. This ΔC P effect is due to the exposure and subsequent hydration of hydrophobic groups. However, for nucleic acids the ΔC P is typically very small and is within the noise level of the baseline. One way to indirectly determine ΔC P is by measuring the unfolding enthalpy, ΔH DSC , and the transition temperature, TM, as a function of salt concentration; the slope of the ΔH DSC versus TM plot is equal to ΔC P . Furthermore, the slope of the TM versus salt concentration plot can be used in conjunction with the thermodynamic parameters obtained from analysis of the DSC thermograms to determine the differential binding of counterions accompanying the unfolding of a macromolecule. In this work, we use DSC to determine ΔC P s for a series of DNA molecules, including ST-DNA, DNA duplexes, stem-loop motifs, hairpins with bulges, intramolecular three- and four-way junctions, triplexes and pseudoknots. In all cases, the resultant ΔC P is small and well within the baseline signal of the DSC and the unfolding of DNA molecules leads to a release of counterions.
Original language | English (US) |
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Title of host publication | Differential Scanning Calorimetry |
Subtitle of host publication | Basics and Applications |
Publisher | Nova Science Publishers, Inc. |
Pages | 1-41 |
Number of pages | 41 |
ISBN (Electronic) | 9781536133363 |
ISBN (Print) | 9781536133356 |
State | Published - Jan 1 2018 |
ASJC Scopus subject areas
- General Engineering
- General Agricultural and Biological Sciences