gyr·​ase ˈjī-ˌrās How to pronounce gyrase (audio)
: a bacterial enzyme that catalyzes the breaking and rejoining of bonds linking adjacent nucleotides in circular DNA to generate supercoiled DNA helices

Word History


gyr- + -ase

First Known Use

1976, in the meaning defined above

Time Traveler
The first known use of gyrase was in 1976

Dictionary Entries Near gyrase

Cite this Entry

“Gyrase.” Dictionary, Merriam-Webster, Accessed 18 Apr. 2024.

Medical Definition


: a bacterial enzyme that is a topoisomerase which catalyzes the ATP-dependent breaking and rejoining of double-strands in circular DNA to generate negative supercoils that twist in the opposite direction as the turns in the original helices

Note: The supercoils introduced by the bacterial gyrase help to relieve the torsional stress in the circular DNA strands that is a consequence of the unwinding of the DNA during replication.

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