[Preparative isolation and study of the reassociation kinetics of a T2 phage DNA fraction containing readily melting regions].

A DNA fraction comprising 6% of total DNA and containing readily-melting regions is isolated from phage T2 DNA using preparative chromatography on MAK columns at T congruent to T m--3 degrees C. Two denaturation regions, differing in the stability for 7 degrees, were observed on this DNA melting curve. A sharp increase of the reassociation rate at initial moments under reassociation temperatures T r approximately less than m --25 degrees C was observed. Thermodynamic characteristics obtained under the repeated melting of DNA fragments after reassociation confirm the fact, that under these reassociation temperatures the incorporation of readily-melting regions into spiral duplexes takes place.