Modified Ising Model Research Articles

On the existence of independently melting subunits in a copolymeric DNA and their statistical distribution

Using a modified Ising model proposed earlier ( Montroll & Goel, 1966) for interpreting the data on the thermal denaturation of DNA molecules with certain reasonable approximations, it is shown that in Escherichia coli and calf thymus DNA, during thermal denaturation in SSC solution, bondings between nucleotides in the two strands break in groups of about 40 bonds, the group rich in AT melting earlier than the one rich in GC. In addition, the relative frequencies of groups of various GC percentages are calculated, thus providing some statistical information about the base sequence in natural DNA molecules.

A semi-empirical analysis of the melting curves of synthetic DNA molecules and the calculation of the stacking and pairing energies and entropies in DNA

A semi-empirical analysis of the available experimental data on the melting temperatures and widths of the melting curves of various synthetic DNA is made using a modified Ising model with the nearest neighbor interactions only. The values for the entropies of denaturation, A-T and G-C bonds energies, and the stacking energies for the various nearest neighbor base pairs are calculated. These values fall within a chemically reasonable range, which suggests that the modified Ising model with the nearest neighbor interactions only, is internally consistent, and satisfactorily describes the melting phenomenon.