On the theory of helix-coil transition in heterogeneous biopolymers. Constrained annealing method

A theory of helix-coil transition in DNA, heteropolymeric with respect to energies of H-bond formation, is considered. The theory is based on the Generalized Model of Polypeptide Chain (GMPC) with employing the constrained annealing method. Expression for the free energy of heteropolymer is derived using transfer-matrix of homopolymer with redefined energy parameter. The technique of calculation of broadening of melting interval depending on the GC-composition and hydrogen bonding energy of AT and GC pairs is developed. Two maxima are revealed on the differential melting curve of heteropolymer. The temperature dependence of the correlation length is considered as well.