Abstract
Thermodynamic stabilities of the liquid crystalline (LC) and gel (G) phases of salmon sperm DNA were investigated by differential scanning calorimetry (DSC). The enthalpic and the entropic components of the thermal denaturation free energy are briefly discussed. In order to evaluate the thermodynamic data for the denaturation of the gel (G) phase of DNA and compare it with those for the LC DNA phase, a hypothesis for the thermal denaturation mechanism of G DNA is proposed. A comparison between these two sets of data has shown that DNA in the LC phase is thermally and thermodynamically more stable than in the G phase over the temperature range which was investigated.