title: Probing the conformational distributions of subpersistence length DNA.
abstract: We have measured the bending elasticity of short double-stranded DNA (dsDNA) chains through small-angle x-ray scattering from solutions of dsDNA-linked dimers of gold nanoparticles. This method, which does not require exertion of external forces or binding to a substrate, reports on the equilibrium distribution of bending fluctuations, not just an average value (as in ensemble fluorescence resonance energy transfer) or an extreme value (as in cyclization), and in principle provides a more robust data set for assessing the suitability of theoretical models. Our experimental results for dsDNA comprising 42-94 basepairs are consistent with a simple wormlike chain model of dsDNA elasticity, whose behavior we have determined from Monte Carlo simulations that explicitly represent nanoparticles and their alkane tethers. A persistence length of 50 nm (150 basepairs) gave a favorable comparison, consistent with the results of single-molecule force-extension experiments on much longer dsDNA chains, but in contrast to recent suggestions of enhanced flexibility at these length scales.
authors.affiliation: Department of Chemistry, University of California, Berkeley, California, USA.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Mastroianni
authors.forename: David A
authors.initials: DA
authors.lastname: Sivak
authors.forename: Phillip L
authors.initials: PL
authors.lastname: Geissler
authors.forename: A Paul
authors.initials: AP
authors.lastname: Alivisatos
mesh_terms: D000465:Algorithms; D001483:Base Sequence; D003198:Computer Simulation; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D004548:Elasticity; D005583:Fourier Analysis; D017612:Gold Compounds; D007700:Kinetics; D053768:Metal Nanoparticles; D008957:Models, Genetic; D009010:Monte Carlo Method; D017711:Nonlinear Dynamics; D009690:Nucleic Acid Conformation; D053838:Scattering, Small Angle; D014965:X-Rays
chemical_list: D017612:Gold Compounds; D004247:DNA