title: Structural determination of the ultraviolet light-induced thymine-cytosine pyrimidine-pyrimidone (6-4) photoproduct.
abstract: Ultraviolet light induces damage to DNA, with the majority of the damage expressed as the formation of cyclobutane dimers and pyrimidine-pyrimidone (6-4) photoproducts. The (6-4) photoproducts have been implicated as important UV light-induced premutagenic DNA lesions. The most abundant of the (6-4) products is the thymine-cytosine pyrimidine-pyrimidone (6-4) photoproduct, or TC (6-4) product. The structure of the TC (6-4) product was deduced by proton NMR, IR, and fast atom bombardment mass spectroscopy, and the product was found to differ from the previously described photoadduct, Thy(6-4)Pyo, by the presence of an amino group at the 5 position of the 5' pyrimidine. The implications of this structure on DNA base pairing and the induction of ultraviolet light-induced mutations are discussed.
mesh_terms: D003596:Cytosine; D004247:DNA / Q000528:radiation effects*; D009682:Magnetic Resonance Spectroscopy; D010777:Photochemistry; D011743:Pyrimidines; D011744:Pyrimidinones; D013054:Spectrophotometry, Atomic; D013055:Spectrophotometry, Infrared; D013941:Thymine; D014466:Ultraviolet Rays
chemical_list: D011743:Pyrimidines; D011744:Pyrimidinones; D003596:Cytosine; D004247:DNA; C030986:pyrimidine; D013941:Thymine