[Effect of selectively reacting ligands on the helix-coil transition of DNA. III. Calculation of the melting curves of DNA-ligand complexes].

The calculation of variations in the helix-coil transition parameters, melting curves and differential melting curves of DNA characteristic of different degree of heterogeneity in the presence of ligands interacting selectively with a certain type or types of base pairs has been carried out. It has been shown that ligands with a selective and non-selective manner of binding influence identically the denaturation process in the case of low DNA heterogeneity (synthetic periodic polynucleotides and satellite DNA fractions). In the case of high heterogeneity (the main fraction of DNA of higher organisms) this influence is quite different. The phenomenon of AT- and GC-base pairs thermostability inversion is considered.