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 (1). Single-stranded nucleic acids are not substrates for this enzyme. A T4 DNA Ligase Technical Bulletin is available.

Applications: Cloning (blunt-end or cohesive-end ligation) (2). Adding linkers or adapters to blunt-ended DNA (2).

Source: Purified from E. coli œ 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 32 P-labeled pyrophosphate, and enzyme in 0.1 ml for 20 min. at 37°C.