T4 DNA Polymerase

T4 DNA Polymerase catalyzes the 5'→3' incorporation of nucleotides into double-stranded DNA using single-stranded and primed DNA as a template. It possesses strong 3'→5' exonuclease (proofreading) activity (100-1000 times stronger than that of Klenow fragment). Unlike E. coli DNA Polymerase I, T4 DNA Polymerase does not have a 5'→3' exonuclease function. Typical T4 DNA polymerase protocols include 5' DNA overhang blunting as well as the generation of blunt double-stranded DNA from double-stranded DNA containing 3' overhangs. These DNA products are often used in blunt cloning.