Flanking sequences modulate diepoxide and mustard cross-linking efficiencies at the 5'-GNC site.
Diepoxybutane, diepoxyoctane, and mechlorethamine are cytotoxic agents that induce interstrand cross-links between the N7 positions of deoxyguanosine residues on opposite strands of the DNA duplex preferentially at 5'-GNC sequences. We have systematically varied the identity of either the base 5' to the cross-linked deoxyguanosine residues or the intervening base pair to determine flanking sequence effects on cross-linking efficiency. We used synthetic DNA oligomers containing four 5'-N(1)GN(2)C sites that varied either N(1) or N(2). Interstrand cross-links were purified through denaturing polyacrylamide gel electrophoresis and then subjected to piperidine cleavage. The amount of cleavage at each deoxyguanosine residue, representative of cross-linking efficiency at that site, was determined by sequencing gel analysis. Our data suggest that cross-linking efficiency varies with the identity of N(1) similarly (purines > pyrimidines) for diepoxybutane, diepoxyoctane, and mechlorethamine but that the effects of N(2) differ for the three compounds.
Department of Chemistry, 5757 Mayflower Hill Drive, Colby College, Waterville, Maine 04901, USA.
Gregory A
GA
Sawyer
Elizabeth D
ED
Frederick
Julie T
JT
Millard
D001483:Base Sequence; D003432:Cross-Linking Reagents / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D003849:Deoxyguanosine / Q000737:chemistry*; D004586:Electrophoresis; D004852:Epoxy Compounds / Q000737:chemistry* / Q000633:toxicity; D008466:Mechlorethamine / Q000737:chemistry* / Q000633:toxicity; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000737:chemistry; D013997:Time Factors
D003432:Cross-Linking Reagents; D004852:Epoxy Compounds; D009841:Oligonucleotides; D008466:Mechlorethamine; D004247:DNA; D003849:Deoxyguanosine