INTERACTIONS WITH NATURAL POLYAMINES AND THERMAL-STABILITY OF DNA - ADSC STUDY AND A THEORETICAL RECONSIDERATION

The effects of different amounts of four natural polyamines on the the rmodynamics of the thermal denaturation of calf thymus and herring spe rm DNA have been studied by means of differential scanning calorimetry . Enthalpy changes and the temperature of the maximum heat effect were determined. The stability of the double helix increases by increasing the polyamine/phosphate ratio and the number of positively charged gr oups on the polyamine molecule. A combination of Manning's polyelectro lyte theory and McGhee and von Hippel's multiple-site exclusion approa ch has been demonstrated to give a very good reproducibility of experi mental results.