title: Force-free measurements of the conformations of DNA molecules tethered to a wall.
abstract: Using an optimized combination of tethered particle motion method, total internal reflection, and a gold nanobead, we measured the three-dimensional distribution of the free end of a tethered DNA molecule. The distribution along the axial z direction (perpendicular to the surface) is found to be Rayleigh-like, in agreement with wormlike chain and freely jointed chain simulations. Using these simulations, we show that the presence of the wall increases the correlations between the orientations of neighboring chain segments compared to free DNA. While the measured and the simulated planar (xy) distributions always agree with that of a Gaussian-random-walk (GRW) model, for short DNA lengths (1 μm) studied in our experiment, the corresponding axial (z) distributions deviate from those predicted for a GRW confined to half-space.
authors.affiliation: Physics Department , Bar Ilan University, Ramat Gan, Israel.
authors.forename: Moshe
authors.initials: M
authors.lastname: Lindner
authors.forename: Guy
authors.initials: G
authors.lastname: Nir
authors.forename: Shlomi
authors.initials: S
authors.lastname: Medalion
authors.forename: Heidelinde R C
authors.initials: HR
authors.lastname: Dietrich
authors.forename: Yitzhak
authors.initials: Y
authors.lastname: Rabin
authors.forename: Yuval
authors.initials: Y
authors.lastname: Garini
mesh_terms: D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D009068:Movement; D009690:Nucleic Acid Conformation
chemical_list: D004247:DNA