Relaxation, linearization and fragmentation of supercoiled circular DNA by tungsten microprojectiles
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Updated: Oct 1, 2026

Genome-wide Purification of Extrachromosomal Circular DNA from Eukaryotic Cells
Published on: April 4, 2016
C Krysiak1, B Mazus, J Buchowicz
1Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland. krishna@ibb.waw.pl
Abstract:
The aim of the study was to characterize DNA lesions caused by microprojectile bombardment and by the post-bombardment presence of tungsten particles in transformed cells. For the sake of simplicity, plasmid DNA was used as a target for bombardment with naked tungsten particles. Unexpectedly extensive DNA degradation was observed under standard bombardment conditions. However, no further DNA fragmentation occurred under post-bombardment conditions, simulated by incubation of plasmid DNA with a suspension of tungsten particles. Instead, relaxation and linearization of supercoiled circular plasmids (pAHC25 and others) took place. It is concluded that the observed linearization (a single site double-strand break in DNA circle) results from the ability of tungsten to catalyse the hydrolysis of phosphodiester bonds in torsionally strained sites of native DNA selectively.
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