title: The reaction of N-methyl-N-nitrosourea with DNA in B and non-B conformations.
abstract: Reaction of N-methyl-N-nitrosourea (MNU) with DNA in B and non-B conformations was investigated using plasmids containing inserts in which the non-B topological isomers could readily be prepared by topoisomerase I catalyzed relaxation in the presence of ethidium. DNA sequences in the Z, cruciform and H conformations were shown to be methylated by MNU at the N7 position of guanines or the N3 position of adenines in a manner that was indistinguishable from the reaction of MNU with the same sequences in the B conformation. Electronic factors rather than steric factors, therefore, appear to dominate methylation of DNA by MNU.
authors.affiliation: Department of Medical Biophysics, University of Toronto, Ontario Cancer Institute, Canada.
authors.forename: J R
authors.initials: JR
authors.lastname: Milligan
authors.forename: S M
authors.initials: SM
authors.lastname: Skotnicki
authors.forename: M C
authors.initials: MC
authors.lastname: Archer
mesh_terms: D001483:Base Sequence; D004247:DNA; D008770:Methylnitrosourea; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides; D010957:Plasmids; D015183:Restriction Mapping
chemical_list: D009838:Oligodeoxyribonucleotides; D008770:Methylnitrosourea; D004247:DNA