Unfolding thermodynamics of nucleic acids: Determining heat capacity effects using differential scanning calorimetry (DSC)

Carolyn E. Carr, Calliste Reiling-Steffensmeier, Irine Khutsishvili, Luis A. Marky

Research output: Chapter in Book/Report/Conference proceedingChapter

1 Scopus citations

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 languageEnglish (US)
Title of host publicationDifferential Scanning Calorimetry
Subtitle of host publicationBasics and Applications
PublisherNova Science Publishers, Inc.
Pages1-41
Number of pages41
ISBN (Electronic)9781536133363
ISBN (Print)9781536133356
StatePublished - Jan 1 2018

ASJC Scopus subject areas

  • Engineering(all)
  • Agricultural and Biological Sciences(all)

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    Carr, C. E., Reiling-Steffensmeier, C., Khutsishvili, I., & Marky, L. A. (2018). Unfolding thermodynamics of nucleic acids: Determining heat capacity effects using differential scanning calorimetry (DSC). In Differential Scanning Calorimetry: Basics and Applications (pp. 1-41). Nova Science Publishers, Inc..