Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Diagrams of topoisomerization and site-specific recombination. (a) DNA Topoisomerization by changing supercoils or decatenation of linked DNA circles. (b) Site-specific recombinases catalyze DNA integration, deletion (also called excision or resolution), and inversion. These reactions require two specific DNA sequences shown as arrows and negative supercols as the energy source. The color versions of all figure are available online.
