title: Conformational flexibility of DNA.
abstract: Pulsed Electron-Electron Double Resonance (PELDOR) on double-stranded DNA (ds-DNA) was used to investigate the conformational flexibility of helical DNA. Stretching, twisting, and bending flexibility of ds-DNA was determined by incorporation of two rigid nitroxide spin labels into a series of 20 base pair (bp) DNA duplexes. Orientation-selective PELDOR experiments performed at both X-band (9 GHz/0.3 T) and G-band (180 GHz/6.4 T) with spin label distances in the range of 2-4 nm allowed us to differentiate between different simple models of DNA dynamics existing in the literature. All of our experimental results are in full agreement with a dynamic model for ds-DNA molecules, where stretching of the molecule leads to a slightly reduced radius of the helix induced by a cooperative twist-stretch coupling.
authors.affiliation: Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt, Germany.
authors.forename: Andriy
authors.initials: A
authors.lastname: Marko
authors.forename: Vasyl
authors.initials: V
authors.lastname: Denysenkov
authors.forename: Dominik
authors.initials: D
authors.lastname: Margraf
authors.forename: Pavol
authors.initials: P
authors.lastname: Cekan
authors.forename: Olav
authors.initials: O
authors.lastname: Schiemann
authors.forename: Snorri Th
authors.initials: ST
authors.lastname: Sigurdsson
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Prisner
mesh_terms: D004247:DNA / Q000737:chemistry*; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D011721:Pyrenes / Q000737:chemistry; D013057:Spectrum Analysis
chemical_list: D011721:Pyrenes; D004247:DNA; C030984:pyrene