title: The presence of two mitochondrial DNA topoisomerases in human acute leukemia cells.
abstract: We have undertaken a study of DNA topoisomerases in mitochondria from human acute leukemia cells. Two activities have been detected in these organelles. One of the enzymes is presumably a type II topoisomerase, i.e., in ATP-dependent reactions it can catenate closed circular plasmid DNA, and decatenate closed circular kinetoplast DNA. A second topoisomerase is presumably a type I enzyme since, it can relax positive as well as negative supercoils in an ATP-independent reaction, it is unable to catenate plasmid DNA or decatenate kinetoplast DNA, and it is inhibited, rather than stimulated, by ATP.
authors.forename: F J
authors.initials: FJ
authors.lastname: Castora
authors.forename: G M
authors.initials: GM
authors.lastname: Lazarus
authors.forename: D
authors.initials: D
authors.lastname: Kunes
mesh_terms: D000208:Acute Disease; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D003421:Crithidia; D004256:DNA Polymerase I / Q000378:metabolism; D004257:DNA Polymerase II / Q000378:metabolism; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D004270:DNA, Circular / Q000032:analysis; D004272:DNA, Mitochondrial / Q000378:metabolism*; D004587:Electrophoresis, Agar Gel; D019286:Endopeptidase K; D010450:Endopeptidases / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000032:analysis; D007945:Leukemia, Lymphoid / Q000201:enzymology* / Q000235:genetics; D008854:Microscopy, Electron; D008970:Molecular Weight; D010957:Plasmids; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology; D014981:Xenopus
chemical_list: D004270:DNA, Circular; D004272:DNA, Mitochondrial; D007527:Isoenzymes; D012967:Sodium Dodecyl Sulfate; D000255:Adenosine Triphosphate; D004256:DNA Polymerase I; D004257:DNA Polymerase II; D010450:Endopeptidases; D019286:Endopeptidase K; D004264:DNA Topoisomerases, Type I