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ISRN Biophysics
Volume 2012 (2012), Article ID 725350, 6 pages
Research Article

Fragmentation of Plasmid DNA Produced by Gamma Radiation: A Theoretical Approach

1Physics Institute, Rua do Matão, Travessa R, No. 187, University of São Paulo, 05508-090 São Paulo, SP, Brazil
2FESP, São Paulo Engineering School, São Paulo, SP, Brazil
3Laboratory of Devices Research, University of Campinas, Campinas, SP, Brazil

Received 16 August 2011; Accepted 18 September 2011

Academic Editor: E. Dague

Copyright © 2012 R. A. S. Silva et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Breaks in DNA, resulting in fragmented parts, can be produced by ionizing radiation which, in turn, is the starting point in the search for novel physical aspects of DNA strands. Double-strand breaks in particular cause disruption of the DNA strand, splitting it into several fragments. In order to study effects produced by radiation in plasmid DNA, a new simple mechanical model for this molecule is proposed. In this model, a Morse-like potential and a high-LET component are used to describe the DNA-radiation interaction. Two power laws, used to fit results of the model, suggest that, firstly, distribution of fragment size is nonextensive and, secondly, that a transition phase is present in the DNA fragment distribution pattern.