Tip I topoizomeraza
Tip I topoizomeraze presecaju jedan lanac dvolančane DNK, relaksiraju molekul, i ponovno spajaju lance.[1][2] One se dalje dele u dve strukturno i mehanistički distinktne topoizomeraze: tip IA i tip IB.
- Tip IA topoizomeraze menjaju koeficijent povezivanja cirkularnog DNK lanca za jednu jedinicu.
- Tip IB topoizomeraze menjaju koeficijent povezivanja za više jedinica .
Istorijski, tip IA topoizomeraze se nazivaju prokariotiske topoizomeraze I, dok se tip IB topoizomeraze nazivaju eukariotske topoizomeraze. Ova distinkcija, međutim nije više primenljiva jer tip IA i tip IB topoizomeraze postoje u svim domenima života.
Funkcionalno, te podklase izvode veoma specijalizovane funkcije. Prokariotska topoizomeraza I (topo IA) može jedino da relaksira negativno supernamotavanje DNK, dok eukariotska topoizomeraza I (topo IB) može da uvede pozitivno supernamotavanje jednolančane DNK, i njenu relaksaciju.
- ↑ Champoux JJ (2001). „DNA topoisomerases: structure, function, and mechanism”. Annu. Rev. Biochem. 70: 369–413. DOI:10.1146/annurev.biochem.70.1.369. PMID 11395412.
- ↑ „National Academy of Sciences: NAS Award in Molecular Biology”. National Academy of Science. Pristupljeno 07. 01. 2009.
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- Branden C, Tooze J.. Introduction to Protein Structure. New York, NY: Garland Publishing. ISBN: 0-8153-2305-0.
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