Effective cross sections for production of single-strand breaks in plasmid DNA by 0.1 to 4.7 eV electrons.

Effective cross sections for production of single-strand breaks in plasmid DNA by 0.1 to 4.7 eV electrons.

Radiation research (2006-04-04)

Radmila Panajotovic, Frédéric Martin, Pierre Cloutier, Darel Hunting, Léon Sanche

ABSTRACT

We determined effective cross sections for production of single-strand breaks (SSBs) in plasmid DNA [pGEM 3Zf(-)] by electrons of 10 eV and energies between 0.1 and 4.7 eV. After purification and lyophilization on a chemically clean tantalum foil, dry plasmid DNA samples were transferred into a high-vacuum chamber and bombarded by a monoenergetic electron beam. The amount of the circular relaxed DNA in the samples was separated from undamaged molecules and quantified using agarose gel electrophoresis. The effective cross sections were derived from the slope of the yield as a function of exposure and had values in the range of 10(-15)- 10(-14) cm2, giving an effective cross section of the order of 10(-18) cm2 per nucleotide. Their strong variation with incident electron energy and the resonant enhancement at 1 eV suggest that considerable damage is inflicted by very low-energy electrons to DNA, and it indicates the important role of pi* shape resonances in the bond-breaking process. Furthermore, the fact that the energy threshold for SSB production is practically zero implies that the sensitivity of DNA to electron impact is universal and is not limited to any particular energy range.

MATERIALS

Product Number

Brand

Product Description

GF97180870

Tantalum, foil, light tested, 50x50mm, thickness 0.01mm, 99.9%

GF24472616

Tantalum, foil, 50mm disks, thickness 0.075mm, annealed, 99.9%

GF64539872

Tantalum, foil, 15mm disks, thickness 0.75mm, annealed, 99.9%

GF39160098

Tantalum, foil, 2m coil, thickness 0.04mm, coil width .65mm, as rolled, 99.9%

GF40567440

Tantalum, foil, 25mm disks, thickness 0.025mm, as rolled, 99.9%

GF47210004

Tantalum, foil, 15mm disks, thickness 0.034mm, as rolled, 99.9%

GF27272167

Tantalum, foil, 8mm disks, thickness 0.025mm, as rolled, 99.9%

GF55544283

Tantalum, foil, 25mm disks, thickness 0.015mm, 99.9%

GF55289548

Tantalum, foil, 15mm disks, thickness 0.5mm, annealed, 99.9%

GF62916318

Tantalum, foil, 10mm disks, thickness 0.75mm, annealed, 99.9%

GF26536057

Tantalum, foil, not light tested, 25x25mm, thickness 0.004mm, 99.9%

GF42889517

Tantalum, foil, light tested, 150x300mm, thickness 0.075mm, annealed, 99.9%

GF29232109

Tantalum, foil, 6mm disks, thickness 0.5mm, annealed, 99.9%

GF15731186

Tantalum, foil, light tested, 25x25mm, thickness 0.01mm, 99.9%

GF50730106

Tantalum, foil, not light tested, 50x50mm, thickness 0.003mm, 99.9%

GF66499891

Tantalum, foil, 6mm disks, thickness 0.02mm, 99.9%

GF63410048

Tantalum, foil, light tested, 50x50mm, thickness 0.0075mm, 99.9%

GF89056648

Tantalum, foil, not light tested, 100x100mm, thickness 0.003mm, 99.9%

GF35633785

Tantalum, foil, light tested, 25x25mm, thickness 0.015mm, 99.9%

GF42443984

Tantalum, foil, not light tested, 100x100mm, thickness 0.01mm, 99.9%

GF91998253

Tantalum, foil, light tested, 100x100mm, thickness 0.025mm, as rolled, 99.9%

GF53850371

Tantalum, foil, light tested, 25x25mm, thickness 0.003mm, 99.9%

GF52742099

Tantalum, foil, light tested, 100x100mm, thickness 0.034mm, as rolled, 99.9%

GF19254472

Tantalum, foil, not light tested, 25x25mm, thickness 0.0005mm, 99.9%

GF15417154

Tantalum, foil, not light tested, 25x25mm, thickness 0.003mm, 99.9%

GF01901539

Tantalum, foil, not light tested, 50x50mm, thickness 0.002mm, 99.9%

GF83507238

Tantalum, foil, light tested, 100x100mm, thickness 0.03mm, as rolled, 99.9%

GF15979494

Tantalum, foil, light tested, 50x50mm, thickness 0.075mm, annealed, 99.9%

GF65369324

Tantalum, foil, light tested, 100x100mm, thickness 0.05mm, annealed, 99.9%

GF00815958

Tantalum, foil, not light tested, 25x25mm, thickness 0.001mm, 99.9%