title: The 5'-GNC site for DNA interstrand cross-linking is conserved for diepoxybutane stereoisomers.
abstract: The bifunctional alkylating agent 1,2,3,4-diepoxybutane forms interstrand DNA-DNA cross-links between the N7 positions of deoxyguanosine residues on opposite strands of the duplex. For racemic diepoxybutane, these cross-links predominate within 5'-GNC/3'CNG sequences, where N is any nucleotide. We used denaturing polyacrylamide gel electrophoresis (dPAGE) to examine the role of stereochemistry in the cross-linking reaction, subjecting a restriction fragment to cross-linking with S,S-DEB, R,R-DEB, or meso-DEB. DNA cross-links generated by each isomer were isolated by dPAGE, and the sites of cross-linking were identified by sequencing gel analysis of DNA fragments generated by hot piperidine cleavage. We found that the 5'-GNC consensus sequence of racemic DEB is conserved, but the efficiencies of cross-linking vary, with S,S- > R,R- > meso-DEB. These results help explain the observed differences between the biological activities of DEB stereoisomers.
authors.affiliation: Department of Chemistry, Colby College, 5757 Mayflower Hill Drive, Waterville, Maine 04901, USA. trety001@umn.edu
authors.forename: Julie T
authors.initials: JT
authors.lastname: Millard
authors.forename: Trevor C
authors.initials: TC
authors.lastname: Hanly
authors.forename: Kris
authors.initials: K
authors.lastname: Murphy
authors.forename: Natalia
authors.initials: N
authors.lastname: Tretyakova
mesh_terms: D000478:Alkylation; D000818:Animals; D001483:Base Sequence; D016384:Consensus Sequence; D003432:Cross-Linking Reagents / Q000737:chemistry*; D004249:DNA Damage; D004275:DNA, Ribosomal / Q000737:chemistry*; D003849:Deoxyguanosine / Q000737:chemistry; D004852:Epoxy Compounds / Q000737:chemistry*; D008969:Molecular Sequence Data; D013237:Stereoisomerism; D014981:Xenopus
chemical_list: D003432:Cross-Linking Reagents; D004275:DNA, Ribosomal; D004852:Epoxy Compounds; C007366:diepoxybutane; D003849:Deoxyguanosine