DNA Ligase (E.coli) catalyzes the formation of a phosphodiester bond between juxtaposed 5’-phosphate and 3’-hydroxyl cohesive termini in duplex DNA. Catalyzes the formation of a phosphodiester bond between duplex DNA fragments with cohesive ends. Condensation of the 5′-phosphoryl group with an adjacent 3′-hydroxyl group is coupled with the hydrolysis of NAD⁺. Suitable for high-efficiency cloning of full-length cDNA.