Two-dimensional random walk and characteristics of helix-coil transition in DNA

On the basis of two-dimensional random walk model, a model of melting of double-stranded DNA is proposed. The expressions for the free energy, the helicity degree and the correlation function of nitrogenous base pair formation, remoted along the chain, are obtained. The temperature dependence of thermodynamic parameters of the model is analyzed. It is shown that the temperature dependence of the helicity degree is qualitatively similar to those obtained in experiments. It is established that the correlation function decays exponentially with increasing distance along the chain between the base pairs.