topoisomerase

noun

topo·​isom·​er·​ase ˌtō-pō-ī-ˈsä-mə-ˌrās How to pronounce topoisomerase (audio)
-ˌrāz
: any of a class of enzymes that reduce supercoiling in DNA by breaking and rejoining one or both strands of the DNA molecule

Examples of topoisomerase in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
When things start getting too tightly wound, topoisomerase cuts the DNA strand, unwinds it, and reattaches it with a bit more slack. — Cathleen O'Grady, Ars Technica, 15 Nov. 2018 Many of these carry drugs that inhibit the enzyme topoisomerase 1, which is essential for DNA replication. — Jyoti Madhusoodanan, Scientific American, 1 Mar. 2024 Each group received different combinations of topoisomerase inhibitors—irinotecan and temozolomide—with or without the monoclonal antibody bevacizumab. — William A. Haseltine, Forbes, 27 Feb. 2025

Word History

Etymology

top- + isomerase

First Known Use

1980, in the meaning defined above

Time Traveler
The first known use of topoisomerase was in 1980

Rhymes for topoisomerase

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Browse Nearby Words

topography
topoisomerase
Topolobampo
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Cite this Entry

“Topoisomerase.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/topoisomerase. Accessed 8 Jul. 2026.

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Medical Definition

topoisomerase

noun
topo·​isom·​er·​ase ˌtō-pō-ī-ˈsäm-ə-ˌrās, -ˌrāz How to pronounce topoisomerase (audio)
: any of a class of enzymes that reduce supercoiling in DNA by breaking and rejoining one or both strands of the DNA molecule
Last Updated: - Updated example sentences
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