Modified self-consistent phonon calculation of the dependence of DNA melting temperature on guanine-cytosine content

We have modified the self-consistent phonon approach to treat DNA double helices modeled with a large repeating unit (N base pairs) so that melting behaviors of DNA polymers of various base-pair sequences can be studied. The melting temperatures of DNA polymers of different G-C–to–A-T ratios were calculated (G, C, A, and T denote guanine, cytosine, adenine, and thymine, respectively). It is shown that a DNA polymer with a relatively higher content of A-T melts at a lower temperature than DNA with a higher content of G-C. The melting temperature increases linearly when the G-C content in a DNA polymer increases. This is in agreement with both experimental observations and theoretical analysis.