title: Recent advances in the synthesis and structure determination of site specifically psoralen-modified DNA oligonucleotides.
abstract: We have developed novel methods for the preparation of multimicromole quantities of extremely pure, uniquely photoadducted psoralen-DNA cross-links, furan-side monoadducted DNA and pyrone-side monoadducts. Psoralen cross-linked and furan-side monoadducted DNA were produced by employing high intensity argon ion and krypton ion lasers as light sources. Pyrone-side monoadducts were prepared by base-catalyzed photoreversal of psoralen cross-links. The various psoralen-adducted DNA oligomers were efficiently purified by high performance liquid chromatography. These methods have permitted us to synthesize 4 mumol each of a self-complementary 8-mer d(GCGTACGC) 4'-(hydroxymethyl)-4,5',8-trimethylpsoralen (HMT) furan-side monoadduct and HMT cross-link. Preliminary nuclear magnetic resonance (NMR) data on the HMT cross-linked 8-mer d(GCGTACGC) have been obtained which confirmed the presence of the diadducted psoralen at the unique 5'TpA3' site. NMR data obtained from the 8-mer furan-side monoadduct revealed that the psoralen molecule is intercalated into the DNA double helix. Preliminary crystals of 8-mer cross-linked DNA molecule have been grown. Conditions for the growth of X-ray diffraction-quality crystals and the further analysis of these crystals are now in progress.
authors.affiliation: Department of Chemistry, University of California, Berkeley.
authors.forename: S S
authors.initials: SS
authors.lastname: Sastry
authors.forename: H P
authors.initials: HP
authors.lastname: Spielmann
authors.forename: T J
authors.initials: TJ
authors.lastname: Dwyer
authors.forename: D E
authors.initials: DE
authors.lastname: Wemmer
authors.forename: J E
authors.initials: JE
authors.lastname: Hearst
mesh_terms: D001483:Base Sequence; D003432:Cross-Linking Reagents; D004247:DNA / Q000737:chemistry; D007834:Lasers; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis / Q000737:chemistry* / Q000528:radiation effects; D014307:Trioxsalen / Q000031:analogs & derivatives*
chemical_list: D003432:Cross-Linking Reagents; D009838:Oligodeoxyribonucleotides; C016507:hydroxymethyltrioxsalen; D004247:DNA; D014307:Trioxsalen