[[Датотека:Gyr.PNG|right|thumb|250px|Struktura 42 -{KDa}- fragmenta -{N}--terminalne ATPaze DNK giraze koja je homologna sa svim drugim tipovima IIA topoizomeraza.]]
'''Tip II [[topoizomeraza|topoizomeraze]]''' presecaju ovaoba lanca DNK heliksa simultano radi upravljanja zamršenjem DNK i supernamotavanjima.<ref name="pmid11395412">{{cite journal | author = Champoux JJ | title = DNA topoisomerases: structure, function, and mechanism | journal = Annu. Rev. Biochem. | volume = 70 | issue = | pages=369-413 | year = 2001 | pmid = 11395412 | doi = 10.1146/annurev.biochem.70.1.369 | url = | issn = }}</ref><ref name="urlNational Academy of Sciences: NAS Award in Molecular Biology">{{cite web | url = http://www.nasonline.org/site/PageServer?pagename=AWARDS_molbio | title = National Academy of Sciences: NAS Award in Molecular Biology | author = | authorlink = | coauthors = | date = | format = | work = | publisher = National Academy of Science | pages = | language = | archiveurl = | archivedate = | quote = | accessdate = 7. 1. 2009. }}</ref> One koriste hidrolizu [[Adenozin trifosfat|ATP-a]], za razliku od tip I [[topoizomeraza]]. U tom procesu, ovi enzimi menjanju [[koeficijent povezivanja]] cirkularne DNK za +/-2.
