Dresden 2006 – wissenschaftliches Programm

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AKB: Biologische Physik

AKB 6: DNA Mechanics

AKB 6.6: Vortrag

Montag, 27. März 2006, 15:45–16:00, ZEU 260

Single Molecule FRET detects sequence dependent Bending and Kinks in DNA — •Filipp Oesterhelt — Heinrich Heine Universität Düsseldorf, Universitätsstrasse 1, Geb. 26.32.02.30, 40225 Düsseldorf

Fluorescence Resonance Energy Transfer (FRET) is a universal tool to measure distances in the range of a few nanometers. This makes FRET ideally suited to analyse distances and distance changes between and within single biomolecules. In the principle accuracy in distance changes is in the sub nanometer range. But the calculation of absolute distances is difficult due to systematic errors. We applied the method of Multiparameter Fluorescence Detection to single DNA doublestrands, internally labelled with a donor and an acceptor fluorophore at various positions. The comparison of the measured energy transfer efficiencies with the fluorophore positions modelled by molecular dynamic simulations revealed that the fluorophore positional and orientational variability has to be taken into account. The absolute distances calculated from our FRET measurements did not only show the helicity of the DNA duplex, but also a sequence dependent bending which was in good agreement with values calculated earlier by NMR and other techniques. We also applied our high precision FRET measurements to the analysis of kinked DNA containing adenosine bulges. From our data we could reconstruct the 3D structure of the kink, revealing the angle, the relative rotation of the helical arms and the offset between their helix axes.