title: Enzymatic excision from gamma-irradiated polydeoxyribonucleotides of adenine residues whose imidazole rings have been ruptured.
abstract: The main forms of base damage in polydeoxyadenylic acid gamma-irradiated under hypoxic conditions are due to saturation and fragmentation of the adenine imidazole ring. An irradiated polymer was annealed with an equimolar amount of poly (dT) to generate a double-stranded polydeoxyribonucleotide containing scattered damaged base residues. On incubation of the latter with partially purified cell extracts of E.coli, imidazole ring-opened adenine, i.e. 4,6-diamino-5-formamidopyrimidine, was released in free form by a DNA glycosylase activity. The enzyme has been purified 4,500-fold, has Mr = 29,000, and appears to be identical with the previously described DNA repair enzyme formamidopyrimidine-DNA glycosylase.
mesh_terms: D000225:Adenine; D043382:DNA-Formamidopyrimidine Glycosylase; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins; D005720:Gamma Rays; D008970:Molecular Weight; D009699:N-Glycosyl Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D011061:Poly A / Q000528:radiation effects*; D011071:Poly T / Q000528:radiation effects*; D011089:Polydeoxyribonucleotides / Q000528:radiation effects*
chemical_list: D029968:Escherichia coli Proteins; D011089:Polydeoxyribonucleotides; D011061:Poly A; D011071:Poly T; C015465:poly(dA); D009699:N-Glycosyl Hydrolases; D043382:DNA-Formamidopyrimidine Glycosylase; C468610:DNA-formamidopyrimidine glycosylase, E coli; D000225:Adenine