منابع مشابه
Writhing Geometry of Open DNA
Motivated by recent experiments on DNA torsion-force-extension characteristics we consider the writhing geometry of open stiff molecules. We exhibit a cyclic motion which allows arbitrarily large twisting of the end of a molecule via an activated process. This process is suppressed for forces larger than femto-Newtons which allows us to show that experiments are sensitive to a generalization of...
متن کاملWrithing Geometry of Stiff Polymers and Scattered Light
The geometry of a smooth line is characterized locally by its curvature and torsion, or globally by its writhe. In many situations of physical interest the line is, however, not smooth so that the classical Frenet description of the geometry breaks down everywhere. One example is a thermalized stiff polymer such as DNA, where the shape of the molecule is the integral of a Brownian process. In s...
متن کاملPlectoneme tip bubbles: Coupled denaturation and writhing in supercoiled DNA
We predict a novel conformational regime for DNA, where denaturation bubbles form at the tips of plectonemes, and study its properties using coarse-grained simulations. For negative supercoiling, this regime lies between bubble-dominated and plectoneme-dominated phases, and explains the broad transition between the two observed in experiment. Tip bubbles cause localisation of plectonemes within...
متن کاملLocal Writhing Dynamics
Randall D. Kamien Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 We present an alternative local definition of the writhe of a self-avoiding closed loop which differs from the traditional non-local definition by an integer. When studying dynamics this difference is immaterial. We employ a formula due to Aldinger, Klapper and Tabor for the change in writh...
متن کاملWrithing Geometry at Finite Temperature: Random Walks and Geometric phases for Stiff Polymers
We study the geometry of a semiflexible polymer at finite temperatures. The writhe can be calculated from the properties of Gaussian random walks on the sphere. We calculate static and dynamic writhe correlation functions. The writhe of a polymer is analogous to geometric or Berry phases studied in optics and wave mechanics. Our results can be applied to confocal microscopy studies of stiff fil...
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ژورنال
عنوان ژورنال: The Journal of Chemical Physics
سال: 2003
ISSN: 0021-9606,1089-7690
DOI: 10.1063/1.1569905