title: Wavelength dependence for the photoreactions of DNA-psoralen monoadducts. 2. Photo-cross-linking of monoadducts.
abstract: The photoreactions of HMT [4'-(hydroxymethyl)-4,5',8-trimethylpsoralen] monoadducts in double-stranded DNA have been studied with complementary oligonucleotides. The HMT was first attached to the thymidine residue in the oligonucleotide 5'-GAAGCTACGAGC-3' as either a furan-side monoadduct or a pyrone-side monoadduct. The HMT-monoadducted oligonucleotide was then hybridized to the complementary oligonucleotide 5'-GCTCGTAGCTTC-3' and irradiated with monochromatic light. In the case of the pyrone-side monoadducted oligonucleotide, photoreversal was the predominant reaction, and very little cross-link was formed at all wavelengths. The course of the photoreaction of the double-stranded furan-side monoadducted oligonucleotide was dependent on the irradiation wavelength. At wavelengths below 313 nm, both photoreversal and photo-cross-linking occurred. At wavelengths above 313 nm, photoreversal of the monoadduct could not be detected, and photo-cross-linking occurred efficiently with a quantum yield of 2.4 X 10(-2).
mesh_terms: D003432:Cross-Linking Reagents / Q000494:pharmacology; D004247:DNA / Q000187:drug effects* / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D004586:Electrophoresis; D005363:Ficusin / Q000378:metabolism / Q000494:pharmacology*; D005663:Furans / Q000378:metabolism; D011564:Furocoumarins / Q000494:pharmacology*; D007700:Kinetics; D011487:Protein Conformation; D011753:Pyrones / Q000378:metabolism; D014307:Trioxsalen / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology*; D014466:Ultraviolet Rays
chemical_list: D003432:Cross-Linking Reagents; D005663:Furans; D011564:Furocoumarins; D011753:Pyrones; C016507:hydroxymethyltrioxsalen; D004247:DNA; D005363:Ficusin; C039281:furan; D014307:Trioxsalen