Enzyme action for topological entanglement in DNA and knot theory

Beside the double helix structure, circular DNA molecules may be knotted or linked. Two interlinked DNA molecules arise during process of replication. They have to be unlinked to allow the separation of the two daughter molecules during cell division. Type II topoisomerases and site-specific recombinases can solve such topological entanglement problems of DNA molecules. We will discuss topological characterizations of the enzyme action using knot theory.