[Some peculiarities of the kinetics of DNA structural transition after thermal jump registered by hyperchromic effect].

Structural transition of DNA is characterized by complex optical kinetic curve. The kinetic version of Felsenfeld's method is used for estimation of concentrations of "denatured" AT- and GC-base pairs in DNA molecules, and the rate constants of the accumulation of "denatured" AT as well as GC pairs have been estimated. The possible interpretation of the kinetic data obtained may be done by assumption that the fast stage of the process reflects the accumulation of the "denatured" AT pairs, which is due to the melting of AT-rich regions in the DNA molecules, whereas the slow stage of the process is limited by the melting of GC-rich regions. In contrast to the fast stage, slow stage takes place at conditions, when unwinded AT-rich regions (loops) may exist in DNA molecules and cause the delay in the process of denaturation.