Mode of drug binding to DNA determined by optical tweezers force spectroscopy |
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| Authors: | I Tessmer C G Baumann G M Skinner J E Molloy J G Hoggett S J B Tendler |
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| Affiliation: | 1. Laboratory of Biophysics and Surface Analysis , School of Pharmaceutical Sciences, University of Nottingham , Nottingham, NG7 2RD, UK;2. Department of Biology , Area 10, University of York , York, YO10 5YW, UK;3. Division of Physical Biochemistry , National Institute for Medical Research , The Ridgeway, Mill Hill, London, NW7 1AA, UK |
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| Abstract: | Abstract Optical tweezers were employed to investigate the effects of small DNA-binding molecules on the low-force (≤ 15 pN) stretching behaviour of single DNA molecules. As the canonical B-DNA helix is not perturbed in this force regime, the effects on DNA elasticity observed upon drug binding provide useful insight into how DNA-binding drugs may alter in vivo processes. In this study, the effects of agents with different DNA binding modes were analysed. DNA force—extension curves were recorded in the presence of netropsin, a purely minor groove-binding antibiotic drug, ethidium bromide, an intercalating fluorescent dye, and berenil, an antiprotozoal drug proposed to exhibit both intercalative and minor groove-binding modes. Applying an approximation of the worm-like chain model, which describes the low-force stretching behaviour, the results were analysed in terms of the DNA contour length and persistence length. From these single molecule studies it was observed that minor groove-binding and intercalating modes of DNA-binding could be distinguished based on changes to DNA elasticity. |
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