DNA ligases.

The DNA ligase enzyme family catalyzes the formation of a phosphodiester bond between juxtaposed 5'-phosphate and 3'-hydroxyl termini in duplex DNA. This activity can seal nicks in duplex DNA or join double-stranded DNA fragments having either blunt or cohesive ends. DNA ligases are central enzymes in molecular biology, nucleic acid research, and in next-generation sequencing applications. Reaction conditions and applications for T4 DNA ligase, E. coli DNA ligase, and thermostable DNA ligases are described in this unit. These enzymes differ in their cofactor requirements, substrate specificity, and thermal stability.