"Maturation" of DNA duplexes.

Reassociation of typical single-copy DNAs, like E. coli DNA, even when performed at relatively low temperatures, results in the formation of perfect duplexes with thermal stability very close to that of the native DNA. In contrast, duplexes of mouse repeated DNA as well as duplexes of Streptomyces DNA prepared under the same conditions, show a low thermal stability and undergo post-reassociation changes upon prolonged incubation. These changes, called "maturation" of the DNA duplexes, result in increasing of their thermal stability. Some of the factors affecting the rate of "maturation" are studied. The implication of the "maturation" process in reassociation analysis and in characterization of the heterogeneity of DNA is discussed.