Application

Suitable for: Ligation of blunt ended or cohesive DNA fragments Ligation of cloning vector and restriction insert fragments Seal nicks in double stranded DNA and RNA or DNA/RNA hybrids Couple RNA single strands by bridging oligonucleotide adapters

Biochem/physiol Actions

T4 DNA Ligase forms an energy dependent phosphodiester linkage between the termini of adjacent polynucleotides of duplex DNA. The ligation reaction requires ATP as a cofactor. Ligation of blunt-ended fragments requires higher enzyme concentration and can be facilitated by using PEG in the reaction mixture. The enzyme requires a 3′ hydroxyl and 5′ phosphate for ligation. Self-ligation of vector DNA can be prevented by dephosphorylation with alkaline phosphatase. T4 ligase plays an active role in repair of DNA and RNA nicks.

Components

T4 DNA Ligase is supplied in a solution containing 20 mM Tris-HCl (pH 7.5), 50 mM KCl, 1 mM DTT, and 50% (v/v) glycerol.

Other Notes

T4 DNA Ligase is inactivated by heating at 65 °C for 10 minutes.

Unit Definition

One Weiss unit is defined as the amount of enzyme required to catalyze the exchange of 1 nmole of P32 from pyrophosphate into ATP as Norit-absorbable material in 20 minutes at 37°C.