title: From toroidal to rod-like condensates of semiflexible polymers.
abstract: The competition between toroidal and rod-like conformations as possible ground states for DNA condensation is studied as a function of the stiffness, the length of the DNA, and the form of the long-range interactions between neighboring molecules, using analytical theory supported by Monte Carlo simulations. Both conformations considered are characterized by a local nematic order with hexagonal packing symmetry of neighboring DNA molecules, but differ in global configuration of the chain and the distribution of its curvature as it wraps around to form a condensate. The long-range interactions driving the DNA condensation are assumed to be of the form pertaining to the attractive depletion potential as well as the attractive counterion induced soft potential. In the stiffness-length plane we find a transition between rod-like to toroid condensate for increasing stiffness at a fixed chain length L. Strikingly, the transition line is found to have a L(1/3) dependence irrespective of the details of the long-range interactions between neighboring molecules. When realistic DNA parameters are used, our description reproduces rather well some of the experimental features observed in DNA condensates.
authors: Center for Computational Physics, Institute of Physics, Vietnam Academy of Science and Technology, 10 Dao Tan St., Hanoi, Vietnam.
authors: Trinh Xuan
authors: TX
authors: Hoang
authors: Dipartimento di Scienze Molecolari e Nanosistemi, Universita' Ca' Foscari Venezia, I-30123 Venezia, Italy.
authors: Achille
authors: A
authors: Giacometti
authors: Department of Theoretical Physics, J. Stefan Institute and Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, SI-1000 Ljubljana, Slovenia and Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA.
authors: Rudolf
authors: R
authors: Podgornik
authors: Center for Computational Physics, Institute of Physics, Vietnam Academy of Science and Technology, 10 Dao Tan St., Hanoi, Vietnam.
authors: Nhung T T
authors: NT
authors: Nguyen
authors: Department of Physics, University of Maryland, College Park, Maryland 20742, USA.
authors: Jayanth R
authors: JR
authors: Banavar
authors: Dipartimento di Fisica, Università di Padova, via Marzolo 8, I-35131 Padova, Italy; CNISM, Unità di Padova, Via Marzolo 8, I-35131 Padova, Italy; and Sezione INFN, Università di Padova, I-35131 Padova, Italy.
authors: Amos
authors: A
authors: Maritan
mesh_terms: D004247:DNA / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009010:Monte Carlo Method; D009690:Nucleic Acid Conformation; D018583:Pliability; D011108:Polymers / Q000737:chemistry*
chemical_list: D011108:Polymers; D004247:DNA