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BP: Fachverband Biologische Physik

BP 7: Posters I

BP 7.3: Poster

Montag, 25. Februar 2008, 17:00–19:30, Poster A

Exact Models for Denaturation Transitions of Nucleic Acids — •Thomas Rudolf Einert and Roland Netz — Technische Universität München, Garching, Germany

Stretching of double-stranded DNA leads to the denaturation of the molecule. A stretching force F≈65 pN leads to a structural transition where DNA changes from its native state (B-DNA) to a stretched state (S-DNA). At even higher forces DNA denatures and the two DNA strands are separated from each other. We present a model with which force-extension curves can be calculated.

Thermodynamics of loops – especially multi-branched loops – in RNA are still not very well understood. We show that the melting curves and the melting temperatures are very sensitive to the modeling of the statistical weight of a loop employing recursion relations to calculate the partition function. Using the asymptotic form for the statistical weight y^mm^−c of a loop of length m known from polymer theory we are able to solve the equations exactly and find a delicate dependence of the critical behavior on the loop exponent c.