Biopolym. Cell. 1987; 3(1):41-43.
ATP-independent DNA topoisomerase from the chloroplasts of Nicotiana chinensis
- N. G. Kholodny Institute of Botany, Academy of Sciences of the Ukrainian SSR
ATP-independent DNA topoisomerase was extracted from the purified leaf chloroplasts of Nicotiana chinensis and partially purified by the salt gradient elution from DEAE-cellulose. Relaxation of negatively supercoiled plasmid pUR222 by the enzyme was found to be absolutely dependent on the presence of magnesium ions, being completely inhibited by EDTA. DNA topoisomerase activity was tolerant to the spermidine (1.8 μg/ml), novobiocin (80 μg/ml) and ethidium bromide (0.8 ng/ml). Strong magnesium requirement of chloroplast DNA topoisomerase in ATP-independent reaction resembles properties of the prokaryotic counterparts.
 Gellert M. DNA topoisomerases. Annu Rev Biochem. 1981;50:879-910.
 Siedlecki J, Zimmermann W, Weissbach A. Characterization of a prokaryotic topoisomerase I activity in chloroplast extracts from spinach. Nucleic Acids Res. 1983;11(5):1523-36.
 Margelis L. role in the evolution of symbiotic cells. - New York: Wiley, 1983. 352 p.
 Ruther U, Koenen M, Otto K, Muller-Hill B. pUR222, a vector for cloning and rapid chemical sequencing of DNA. Nucleic Acids Res. 1981;9(16):4087-98.
 Endocytobiology. Eds H. E. A. Schenk, W. Schwemmler. - Berlin; New York : Walter de Gruyter, 1983. V. 2. 891 p.
 Bogorad L. Evolution of organelles and eukaryotic genomes. Science. 1975;188(4191):891-8.
 Srivenugopal KS, Lockshon D, Morris DR. Escherichia coli DNA topoisomerase III: purification and characterization of a new type I enzyme. Biochemistry. 1984;23(9):1899-906.
 Kung VT, Wang JC. Purification and characterization of an omega protein from Micrococcus luteus. J Biol Chem. 1977;252(15):5398-402.
 Kikuchi A, Asai K. Reverse gyrase--a topoisomerase which introduces positive superhelical turns into DNA. Nature. 1984 Jun 21-27;309(5970):677-81.
 Brown PO, Peebles CL, Cozzarelli NR. A topoisomerase from Escherichia coli related to DNA gyrase. Proc Natl Acad Sci U S A. 1979;76(12):6110-4.
 Richardson SM, Higgins CF, Lilley DM. The genetic control of DNA supercoiling in Salmonella typhimurium. EMBO J. 1984;3(8):1745-52.