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Biochem Biophys Res Commun. 1984 May 31;121(1):77-86.

Isolation of a mitochondrial DNA topoisomerase from human leukemia cells.


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.

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