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.
Reference
[уреди | уреди извор]- ^ Champoux JJ (2001). „DNA topoisomerases: structure, function, and mechanism”. Annu. Rev. Biochem. 70: 369—413. PMID 11395412. doi:10.1146/annurev.biochem.70.1.369.
- ^ „National Academy of Sciences: NAS Award in Molecular Biology”. National Academy of Science. Приступљено 7. 1. 2009.
Literatura
[уреди | уреди извор]- Nicholas C. Price; Lewis Stevens (1999). Fundamentals of Enzymology: The Cell and Molecular Biology of Catalytic Proteins (Third изд.). USA: Oxford University Press. ISBN 019850229X.
- Eric J. Toone (2006). Advances in Enzymology and Related Areas of Molecular Biology, Protein Evolution (Volume 75 изд.). Wiley-Interscience. ISBN 0471205036.
- Branden C; Tooze J. Introduction to Protein Structure. New York, NY: Garland Publishing. ISBN 0-8153-2305-0.
- Irwin H. Segel. Enzyme Kinetics: Behavior and Analysis of Rapid Equilibrium and Steady-State Enzyme Systems (Book 44 изд.). Wiley Classics Library. ISBN 0471303097.
Spoljašnje veze
[уреди | уреди извор]- DNA+Topoisomerases,+Type+I на US National Library of Medicine Medical Subject Headings (MeSH)
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