Thymine lesions produced by ionizing radiation in double-stranded DNA.
A DNA glycosylase which catalyzes the release of thymine residues damaged by ring saturation, fragmentation, or ring contraction from double-stranded DNA has been used to characterize such base derivatives in gamma-irradiated DNA. It is shown by chromatographic analysis that irradiation of DNA in neutral solution generates the ring-saturated forms cis-thymine glycol, trans-thymine glycol, and a monohydroxydihydrothymine, probably 6-hydroxy-5,6-dihydrothymine. The latter compound is only observed after irradiation under hypoxic conditions. The ring-contracted thymine derivative 5-hydroxy-5-methylhydantoin is also formed, and it is the major lesion after irradiation of DNA under O2. Ring-fragmented products such as methyltartronylurea were only generated in small quantities. Isolation and analysis of the DNA from gamma-irradiated human cells also revealed the formation of ring-saturated thymine derivatives, but 5-hydroxy-5-methylhydantoin was not found in this case.
D001402:B-Lymphocytes; D002051:Burkitt Lymphoma; D002460:Cell Line; D004247:DNA / Q000302:isolation & purification / Q000528:radiation effects*; D045647:DNA Glycosylases; D004270:DNA, Circular / Q000528:radiation effects; D004273:DNA, Neoplasm / Q000528:radiation effects; D043224:Deoxyribonuclease (Pyrimidine Dimer); D004926:Escherichia coli / Q000201:enzymology; D005720:Gamma Rays; D006801:Humans; D009699:N-Glycosyl Hydrolases; D010957:Plasmids; D013941:Thymine / Q000528:radiation effects*
D004270:DNA, Circular; D004273:DNA, Neoplasm; D004247:DNA; D043224:Deoxyribonuclease (Pyrimidine Dimer); D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; D013941:Thymine