Denaturation and renaturation of DNA. I. Equilibrium statistics of copolymeric DNA

The one‐dimensional Ising model, with nearest neighbor correlation only, suitably modified, is used to explain the observed linear dependence of melting temperature of copolymeric DNA with GC content. Transition curves are plotted for regular, random, and Markoff distribution of base pairs for various values of a correlation parameter U between nearest neighbor bonds. Exact analytic formulas are given for fraction of bonds intact at a particular temperature for various regular distributions for all U and approximate ones for random and Markoff distributions for small U . A scheme is indicated for further improvement. The model, in principle, makes it possible to estimate the statistical distribution of base pairs from the detailed shape of the transition curve.