title: DNA damage caused by ascorbate in the presence of Cu2+ induces mutations.
abstract: The DNA damage induced by ascorbate in the presence of Cu2+ was analyzed by sequencing, and the mutagenic consequences of damages to plasmid pUC18 lacZ' were assayed in a forward repairing system in E. coli JM109 in vivo. Ascorbate induced two classes of DNA damage in the presence of Cu2+, one being non-base-specific direct strand cleavage, and the other being sequence-specific base modification labile to alkali treatment. Radicals generated from ascorbate hydroperoxide were involved in DNA damaging reactions. Ascorbate and Cu2+ caused mutations in pUC18 lacZ' gene. The mutation frequency by this method was about 10(-4) at 18% survivors when measured as a loss of alpha-complementation. All the mutations found were single-base substitutions that occurred in the structural part of the lacZ' gene. They were predominantly G:C----A:T transitions.
authors.affiliation: Department of Agricultural Chemistry, Kyoto University, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kobayashi
authors.forename: K
authors.initials: K
authors.lastname: Yoshida
authors.forename: K
authors.initials: K
authors.lastname: Ueda
authors.forename: H
authors.initials: H
authors.lastname: Sakai
authors.forename: T
authors.initials: T
authors.lastname: Komano
mesh_terms: D001205:Ascorbic Acid / Q000494:pharmacology*; D001483:Base Sequence; D003300:Copper / Q000494:pharmacology*; D004249:DNA Damage; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial / Q000187:drug effects; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids / Q000187:drug effects*
chemical_list: D003300:Copper; D001205:Ascorbic Acid