DNA ligase is used in both DNA repair and DNA replication (see Mammalian ligases). In addition, DNA ligase has extensive use in molecular biology laboratories for recombinant DNA experiments (see Research applications). Purified DNA ligase is used in gene cloning to join DNA molecules together to form recombinant DNA.

What is DNA ligase used for?

DNA ligases catalyze the formation of phosphodiester bonds between juxtaposed 5' phosphate and a 3'-hydroxyl terminus in duplex DNA. This activity can repair single-stranded nicks in duplex DNA and join duplex DNA restriction fragments having either blunt ends or homologous cohesive ends.

In which step would the enzyme ligase be used?

Ligase, an enzyme that uses ATP to form bonds, is used in recombinant DNA cloning to join restriction endonuclease fragments that have annealed.