A type of enzyme converting (isomerizing) one topological version of DNA into another; acts by catalyzing the breakage and reformation of DNA phosphodiester linkages. [topo- + isomerase]
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topo·isom·er·ase .tō-pō-ī-'säm-ə-.rās, -.rāz n any of a class of enzymes that reduce supercoiling in DNA by breaking and rejoining one or both strands of the DNA molecule
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topo·isom·er·ase (to″po-i-somґə-rās) an enzyme that interconverts topoisomers of DNA by breaking and rejoining one or more phosphodiester bonds and altering the degree of supercoiling of the DNA.Medical dictionary. 2011.