title: Malondialdehyde precursors in gamma-irradiated DNA, deoxynucleotides and deoxynucleosides.
abstract: Gamma-irradiation of DNA, deoxynucleosides, or deoxynucleotides produces material that reacts with thiobarbituric acid to form a chromophore with maximum absorbance at 532 nm. This material is not malondialdehyde. We have identified a new radiation product (thymin-1'-yl)-propenal as the TBA-reactive product of gamma-irradiation of thymidine. Thymine-propenal has been described by other investigators as a product of bleomycin-treatment of DNA. Irradiation of thymidine nucleotides produces phosphorylated precursors to thymine-propenal. Studies of the requirements for formation of TBA-reactivity indicate a mechanism involving reaction of a free radical with the deoxyribose moiety and molecular oxygen. On the basis of these results it is proposed that gamma-irradiation produces TBA-reactive material in DNA by the same reaction sequence in which bleomycin catalyzes the formation of base-propenals in DNA. Bleomycin and gamma-irradiation differ in the extent to which the sequence proceeds to completion with release of free base-propenals.
mesh_terms: D000388:Air; D004247:DNA / Q000528:radiation effects*; D003853:Deoxyribonucleosides / Q000528:radiation effects*; D003854:Deoxyribonucleotides / Q000528:radiation effects*; D005609:Free Radicals; D005720:Gamma Rays; D008314:Malonates; D008315:Malondialdehyde; D009584:Nitrogen; D009609:Nitrous Oxide; D010100:Oxygen; D013858:Thiobarbiturates
chemical_list: D003853:Deoxyribonucleosides; D003854:Deoxyribonucleotides; D005609:Free Radicals; D008314:Malonates; D013858:Thiobarbiturates; D008315:Malondialdehyde; D004247:DNA; D009609:Nitrous Oxide; C029684:thiobarbituric acid; D009584:Nitrogen; D010100:Oxygen