Calorimetry: A tool for DNA and ligand—DNA studies

This chapter discusses the unique information that can be obtained by the application of selected calorimetric techniques to the study of DNA. The chapter demonstrates calorimetry to be a powerful tool in biophysical research, capable of uniquely providing thermodynamic and extrathermodynamic characterizations of DNA structure, conformational transitions, and ligand interactions. A differential scanning calorimeter is an instrument that allows to measure continuously the heat capacity of a system as a function of temperature. Isothermal mixing calorimetry has been used in nucleic acid studies to characterize the influence of metal ion binding; to determine the enthalpy of duplex formation from the mixing of two complementary strands; to measure the energetics of pH-induced changes in nucleic acid structure; and to determine the enthalpy of small ligand-DNA interactions and protein–DNA interactions. Multifrequency calorimetry has been applied to the analysis of membrane phase transitions and to the folding–unfolding transition of the protein cytochrome c.