Dresden 2006 – scientific programme

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AKB: Biologische Physik

AKB 6: DNA Mechanics

AKB 6.2: Talk

Monday, March 27, 2006, 14:45–15:00, ZEU 260

An Intermediate Phase in DNA Melting — •Richard A. Neher and Ulrich Gerland — Arnold Sommerfeld Center for Theoretical Physics (ASC) and Center for NanoSciene (CeNS), LMU München

We predict a novel temperature-driven phase transition of DNA below the melting transition. The additional, intermediate phase exists for repetitive sequences, when the two strands have different lengths. In this phase, the longer strand is completely absorbed onto the shorter strand. The excess bases form mobile bulge loops inside the helical region. Below the transition temperature, more and more of these bulge loops condense into overhanging single stranded ends. We calculate the partition sum of such DNA exactly and find, that this transition is continuous and in many aspects analogous to Bose-Einstein condensation. When the periodicity of the sequence is destroyed by rare point mutations, the transition becomes discontinous. Furthermore, we find that the order of the melting transition of repetitive DNA differs from that of ordinary DNA.

[1] R.A. Neher and U. Gerland, qbio.BM/0509015