DNA Polymerase I (5000 U)

QIAGEN DNA Polymerase I is a mesophilic, DNA-dependent DNA polymerase that catalyzes 5'-3' DNA synthesis and carries both 3'→5' and 5'→3' exonuclease activities. Together, the polymerase and 5'→3' nuclease functions enable nick-translation, in which nucleotides ahead of a growing DNA chain are removed and replaced in the 5' to 3' direction. The enzyme is produced by a recombinant E. coli strain carrying the PolA gene.

Reported assay specifications include >99% purity and a specific activity of 6850 U/mg. Both single-stranded and double-stranded exonuclease activities are functional, while double-stranded endonuclease activity shows no conversion at 200 U, and E. coli DNA contamination is reported at <10 copies per 200 U. The enzyme is supplied in 25 mM Tris-HCl, 0.1 mM EDTA, 1.0 mM dithiothreitol and 50% glycerol at pH 7.4 (25°C), together with a 10X Blue Buffer containing 500 mM NaCl, 100 mM Tris-HCl, 100 mM MgCl₂ and 10 mM DTT at pH 7.9 (25°C). Third-party guidance recommends storage at –25°C to –15°C.