Type II topoisomerase
DNA Topoisomerases regulate the number of topological links between two DNA strands[1]. Type II topoisomerases alter DNA Topology using an active strand passage mechanism. This mean they create a doublestranded break in a DNA duplex and alter the number of supercoils in a region of DNA by passing a different DNA duplex through this temporary or transient break in the DNA, this mechanism requires the use of ATP thus making it an active process. Type II Topoisomerases can be split into two classes; Aand B.
Type A are found in all cell-based organisms in addition to some viruses while type B are found in Archae, Plants as well as some Bacteria. These enzyme types are both able to relax both positive and negative supercoils with some exceptions in function e.g. Type IIA Bacterial Gyrase which increases negative supercoiling in DNA. These enzymes differ in both the Primary sequence and structure of their DNA-Cleavage and ATPase domains as well as the organisms they are found in[2].