T4 DNA Ligase catalyses the formation of a phosphodiester bond between the terminal 5′ phosphate and 3′ hydroxyl groups of duplex DNA or RNA. The enzyme efficiently joins blunt and cohesive ends and repairs single stranded nicks in duplex DNA, RNA or DNA/RNA hybrids.

10X T4 DNA Ligase Buffer is composed of 500 mM Tris-HCI, 100 mM MgCl ₂, 50 mM dithiothreitol, 10 mM ATP, pH 7.6 @ 25 °C.

2X Rapid Ligation Buffer is composed of 132 mM Tris-HCI, 20 mM MgCl ₂, 2 mM dithiothreitol, 2 mM ATP, 15% PEG, pH 7.6 @ 25 °C.

Figure 1: Purity
The purity of the T4 DNA ligase is equal or greater than 95% as judged by SDS-polyacrylamide gel electrophoresis with Coomassie blue staining. Molecular weight markers are in Lane 1. T4 DNA ligase was loaded at 5 units (Lane 2) and 10 units (Lane 3).

Figure 2: Exonuclease and Endonuclease Activity Assay
The T4 DNA ligase is free of detectable of exo- and endonuclease activities, as judged by agarose gel electrophoresis following incubation of 10 units of enzyme for 16 hours at 37 °C with 1 µg of HindIII-digested λ DNA (Lanes 3 and 4) and supercoiled pUC19 DNA (Lanes 5 and 6). Molecular weight markers are in Lanes 1 and 2.