title: Base-catalyzed reversal of a psoralen-DNA cross-link.
abstract: Base-catalyzed reversal of a psoralen-DNA cross-link has been observed under denaturing alkaline conditions at elevated temperatures. The cross-link was formed between 4'-(hydroxymethyl)-4,5',8-trimethylpsoralen and the two thymidine residues (T) on opposite strands of the double-stranded DNA formed from the self-complementary oligonucleotide 5'-GGGTACCC-3'. In contrast to the photoreversal of the cross-link, which yields mostly the furan-side monoadducted oligonucleotide [Cimino, G. D., Shi, Y., & Hearst, J. E. (1986) Biochemistry 25, 3013-3020], base-catalyzed reversal of the cross-link yields only pyrone-side monoadducted oligonucleotides as identified on the basis of their mobilities on a 20% polyacrylamide-7 M urea gel and their chemical and photochemical properties. A mechanism has been proposed to explain the base-catalyzed reversal reaction. This observation suggests a way to make pyrone-side monoadducted DNA. It also suggests that caution must be taken when psoralen-adducted DNA is treated under denaturing alkaline conditions.
authors.affiliation: Department of Chemistry, University of California, Berkeley 94720.
authors.forename: Y B
authors.initials: YB
authors.lastname: Shi
authors.forename: H P
authors.initials: HP
authors.lastname: Spielmann
authors.forename: J E
authors.initials: JE
authors.lastname: Hearst
mesh_terms: D002851:Chromatography, High Pressure Liquid; D003432:Cross-Linking Reagents / Q000378:metabolism*; D004247:DNA / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D011564:Furocoumarins / Q000378:metabolism*; D009841:Oligonucleotides / Q000032:analysis; D014307:Trioxsalen / Q000031:analogs & derivatives / Q000378:metabolism*
chemical_list: D003432:Cross-Linking Reagents; D011564:Furocoumarins; D009841:Oligonucleotides; C016507:hydroxymethyltrioxsalen; D004247:DNA; D014307:Trioxsalen