T4 DNA Ligase catalyzes the formation of phosphodiester bonds in the presence of ATP between double-stranded DNAs with 3´ hydroxyl and 5´ phosphate termini. The unique T4 DNA Ligase buffer optimizes ligation, which can be performed in 5 minutes. Single-stranded nucleic acids are not substrates for this enzyme.

Applications
Cloning (blunt-end or cohesive-end ligation) and adding linkers or adapters to blunt-ended DNA

Source
Purified from E. coli lambda lysogen NM989

Performance and quality testing
Endodeoxyribonuclease, 3´ and 5´ exodeoxyribonuclease assays; ligation efficiency tested

Unit definition
One unit catalyzes the exchange of 1 nmol ³²P-labeled pyrophosphate into ATP in 20 min at 37°C. One unit is equal to approximately 300 cohesive-end ligation units.

Unit reaction conditions
66 mM Tris-HCl (pH 7.6), 6.6 mM MgCl₂, 10 mM DTT, 66 μM ATP, 3.3 μM ³²P-labeled pyrophosphate, and enzyme in 0.1 mL for 20 min at 37°C.