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Isolation of a mitochondrial DNA topoisomerase from human leukemia cells. 1984

F J Castora, and G M Lazarus

Mitochondria from human acute lymphoblastic leukemia cells contain an ATP-independent DNA topoisomerase which can relax negative and positive supercoils. This enzyme has been purified 200-fold by carboxymethyl-cellulose or double stranded DNA-cellulose chromatography. In contrast to the molecular weights reported for mitochondrial topoisomerases in other systems, the native leukemia enzyme has a molecular weight of 132,000 daltons as determined by gel permeation chromatography in buffer containing 0.4 M KC1. It also exhibits a sedimentation coefficient of 7.1 S when centrifuged through a 10-30% glycerol gradient in this high salt buffer. The enzyme is presumably a type I topoisomerase analogous to those found in rat liver and Xenopus laevis mitochondria.

UI MeSH Term Description Entries
D007945 Leukemia, Lymphoid Leukemia associated with HYPERPLASIA of the lymphoid tissues and increased numbers of circulating malignant LYMPHOCYTES and lymphoblasts. Leukemia, Lymphocytic,Lymphocytic Leukemia,Lymphoid Leukemia,Leukemias, Lymphocytic,Leukemias, Lymphoid,Lymphocytic Leukemias,Lymphoid Leukemias
D008928 Mitochondria Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed) Mitochondrial Contraction,Mitochondrion,Contraction, Mitochondrial,Contractions, Mitochondrial,Mitochondrial Contractions
D008970 Molecular Weight The sum of the weight of all the atoms in a molecule. Molecular Weights,Weight, Molecular,Weights, Molecular
D011489 Protein Denaturation Disruption of the non-covalent bonds and/or disulfide bonds responsible for maintaining the three-dimensional shape and activity of the native protein. Denaturation, Protein,Denaturations, Protein,Protein Denaturations
D002845 Chromatography Techniques used to separate mixtures of substances based on differences in the relative affinities of the substances for mobile and stationary phases. A mobile phase (fluid or gas) passes through a column containing a stationary phase of porous solid or liquid coated on a solid support. Usage is both analytical for small amounts and preparative for bulk amounts. Chromatographies
D004264 DNA Topoisomerases, Type I DNA TOPOISOMERASES that catalyze ATP-independent breakage of one of the two strands of DNA, passage of the unbroken strand through the break, and rejoining of the broken strand. DNA Topoisomerases, Type I enzymes reduce the topological stress in the DNA structure by relaxing the superhelical turns and knotted rings in the DNA helix. DNA Nicking-Closing Protein,DNA Relaxing Enzyme,DNA Relaxing Protein,DNA Topoisomerase,DNA Topoisomerase I,DNA Topoisomerase III,DNA Topoisomerase III alpha,DNA Topoisomerase III beta,DNA Untwisting Enzyme,DNA Untwisting Protein,TOP3 Topoisomerase,TOP3alpha,TOPO IIIalpha,Topo III,Topoisomerase III,Topoisomerase III beta,Topoisomerase IIIalpha,Topoisomerase IIIbeta,DNA Nicking-Closing Proteins,DNA Relaxing Enzymes,DNA Type 1 Topoisomerase,DNA Untwisting Enzymes,DNA Untwisting Proteins,Topoisomerase I,Type I DNA Topoisomerase,III beta, Topoisomerase,III, DNA Topoisomerase,III, Topo,III, Topoisomerase,IIIalpha, TOPO,IIIalpha, Topoisomerase,IIIbeta, Topoisomerase,Topoisomerase III, DNA,Topoisomerase, TOP3,beta, Topoisomerase III
D004272 DNA, Mitochondrial Double-stranded DNA of MITOCHONDRIA. In eukaryotes, the mitochondrial GENOME is circular and codes for ribosomal RNAs, transfer RNAs, and about 10 proteins. Mitochondrial DNA,mtDNA
D004273 DNA, Neoplasm DNA present in neoplastic tissue. Neoplasm DNA
D004278 DNA, Superhelical Circular duplex DNA isolated from viruses, bacteria and mitochondria in supercoiled or supertwisted form. This superhelical DNA is endowed with free energy. During transcription, the magnitude of RNA initiation is proportional to the DNA superhelicity. DNA, Supercoiled,DNA, Supertwisted,Supercoiled DNA,Superhelical DNA,Supertwisted DNA
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man

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