The hierarchical approach to the DNA stability problem. I. Patterns in non-equilibrium denaturation and renaturation.

As proposed by Azbel (Phys. Rev. Letters, 1973, 31, 589-592), DNA sequences may be uniquely divided into embedded segments with different lengths and stabilities, each of them a potential denaturation unit. This "hierarchical" approach to the DNA stability problem was originally devised for the analysis of equilibria situations. We have extended it to deal quantitatively with various locally irreversible denaturation/renaturation processes that play a leading part in most actual experiments. Special emphasis is placed on (1) describing and delimiting major experimental domains with respect to reversibility/irreversibility, and (2) the quantitative treatment of bidirectional denaturation processes which are shown to lend themselves to an original, hierarchical analysis.