Product name: Topoisomerase
EC number: type I: EC 5.99.1.2, type II: EC 5.99.1.3
Product Description:
Topoisomerases are enzymes that unwind and wind DNA, in order for DNA to control the synthesis of proteins, and in order for DNA to reproduce. They cut the DNA, and at the end of the process connect it again.
Topoisomerases are isomerase enzymes that act on the topology of DNA.
Function:
The double-helical configuration that DNA strands naturally reside in makes them difficult to separate, and yet they must be separated by helicase proteins if other enzymes are to transcribe the sequences that encode proteins, or if chromosomes are to be replicated. In so-called circular DNA, in which double helical DNA is bent around and joined in a circle, the two strands are topologically linked, or knotted. Otherwise identical loops of DNA having different numbers of twists are topoisomers, and cannot be interconverted by any process that does not involve the breaking of DNA strands. Topoisomerases catalyze and guide the unknotting of DNA by creating transient breaks in the DNA using a conserved Tyrosine as the catalytic residue.
The insertion of viral DNA into chromosomes and other forms of recombination can also require the action of topoisomerases.
