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DNA NICKING BY ULTRAVIOLET RADIATION IS ENHANCED IN THE PRESENCE OF IRON and OF OXYGEN
Author(s) -
Audic Annie,
Giacomoni Paolo U.
Publication year - 1993
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1993.tb02327.x
Subject(s) - phosphodiester bond , covalent bond , chemistry , agarose , dna , agarose gel electrophoresis , irradiation , ferric , in vitro , oxygen , photochemistry , nuclear chemistry , biophysics , biochemistry , inorganic chemistry , biology , organic chemistry , rna , physics , nuclear physics , gene
Double‐stranded covalently closed circular supercoiled DNA (ccc DNA) from plasmid pUK 9 was irradiated in vitro at denned wavelengths in the UV region (290, 313 and 365 nm). The nicking was monitored by electrophoresis on agarose gels, ethidium staining and densitometric quantitation of supercoiled and relaxed moieties. At the explored wavelengths, the dose required for introducing one nick per million phosphodiester bonds diminishes with increased concentration of added ferric iron, whereas the effect of cupric iron is practically negligible. Adding metal chelators or bubbling argon prior to the irradiation results in a dramatic increase in the dose required for introducing one nick per million phosphodiester bonds. Taken together, these results seem to indicate that iron and oxygen play a role as cofactors in the UV‐induced nicking of ccc DNA in vitro .